Ford 4000 wont turn over

First time posting - 1964 ford Ag. light industrial 4000, 172 CID 4cyl. (41305) select-o-speed trans. 540 PTO, front loader and a removable 753 backhoe. History - I purchased the tractor 2 years ago an used it for year. Changed oil and filter a couple of times. Ran a little week but I love this tractor. I changed plugs, distributor cap, rotor and points once, after it quit running, an it fired back up like usual.
October of last year, I had to replace the water pump (I think I over tightened the belt), and decided to power wash the machine. I started it up and sprayed it off good. I let it run a little longer and then shut it off. Next day I decided to remove the backhoe to repair a leaky right rear tire and to power spray the hoe. I started it up, got to flat ground, turned it off and removed the backhoe. It turned over really slow and wouldn't start again. I checked for moisture in the distributor, and anywhere I thought it might be a problem, etc.. it sat for a few weeks while I asked around and tried to figure out what to do next.
I discovered worn but working distributor cam weights, a starter motor that was filthy but cleaned up OK and turned fast when attached to a 6 volt battery and a host of old worn wiring. I replaced suspect wiring. It still struggled to turn over and wouldn't start so I got a mechanic friend to look at it with me. We found very low compression, and he commented that he didn't think the starter was turning fast enough. Based on the compression - I decided to pull the head and have a look see. over the next few months I have....
Head cleaned up and a machine shop did the valves.
After I found a couple of broken rings,I carefully honed the cylinders an installed...
New rings and main bearings.
New starting and charging circuits wiring
New plug wires, spark plugs, distributor cap, points,condenser,& coil
New starter
New battery
I also decided, while it was down, to replace the rear wheel bearings to get rid of the side to side slop in the rear end.
I have also replaced the rear end gear oil, hydraulic oil, and transmission hydraulic fluid and clean up the transmission screen filter.
Now - after all this - It still won't turn over. Starter won't make one complete turn.
I suspect some rusty, locked up something or other but could sure use a point in the right direction. I am thinking about removing the front cover to look at timing gears and the governor assembly. Any ideas before I waste more time and money? Thanks to any who respond

The first answer to your question every time that it comes up is battery cables and starter cable. You don't mention these. maybe half the time the original poster insists for a week or two of debate that his cables and terminals are like new and that it can't be anything so simple. Probably one of ten finally goes away mad insisting that his cables and connections are good.

Showcrop is on the mark. I had all kinds of trouble starting my Farmall for several years. I converted to 12 volt, replaced the starter and still had very slow cranking. When I started to strip back the battery
cables to put on new ends, I discovered that the wire inside the insulation was all corroded. With new cables, it will crank fast enough to make oil pressure!

Thank you - I forgot to add new battery cables and starter cable as well. all #2 cooper. I am a little dubious about the solenoid. I did however take the starter cable and hold it directly to the battery terminal to check to see if it would turn any better. it didn't. Thanks!

Thank you - I forgot to add new battery cables and starter cable as well. all #2 cooper. I am a little dubious about the solenoid. I did however take the starter cable and hold it directly to the battery terminal to check to see if it would turn any better. it didn't. Thanks!

(quoted from post at 11:19:40 03/04/17) Thank you - I forgot to add new battery cables and starter cable as well. all #2 cooper. I am a little dubious about the solenoid. I did however take the starter cable and hold it directly to the battery terminal to check to see if it would turn any better. it didn't. Thanks!

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12V should be 0 gauge, 6V should be 00.

You are right. Seen cables/connections go bad way too many times. On the side... anyone wants to test this with their voltmeter- check battery voltage while cranking, then at the solenoid, then at the starter. There will be slight drop but if seeing several volts- there is the problem. Don't forget the ground side too!

What about pull starting it? Make sure the engine will run.
With honed cylinders and new rings, it may be
hard to turn over the first couple times.
(You did remove the cylinder wear ridge and set the ring gaps
appropriately? Are the new bearings putting a death grip
on the crankshaft? Use plenty of assembly grease.)
I live in hill country, so I roll down a hill to start
a stiff engine. After a half hour of running, it gets
easier to crank.

(quoted from post at 19:29:50 03/04/17) What about pull starting it? Make sure the engine will run.
With honed cylinders and new rings, it may be
hard to turn over the first couple times.
(You did remove the cylinder wear ridge and set the ring gaps
appropriately? Are the new bearings putting a death grip
on the crankshaft? Use plenty of assembly grease.)
I live in hill country, so I roll down a hill to start
a stiff engine. After a half hour of running, it gets
easier to crank.

Click to expand...

One can't pull start an SOS. Were you just not thinking, or did you really not know this?

Not thinking