D-14 ????????

Newbie to the site. I normally am a Farmall man. I've taken on a project to overhaul a D-14 for the wife's uncle. I've totally overhauled the engine. New radiator, hoses, water pump, new pistons, rings, head reworked, new bearings after the crank was ground, new exhaust manifold, carb overhaul, etc. Rewired the whole tractor. Working on the rear end as well. Left brake is shot, right one just barely works. New rear tires, old ones are shot with chunks missing and more coming out of the casings. (PIA to get rid of the calcium chloride) Anyway,

Question #1 It will not start. It ran when I pulled it into the garage. The timing is set to factory specs. I've installed a new carb kit including a new valve and seat. Even with the gas shut off, I get liquid fuel in the intake of the carb while I'm cranking it over. I did find the float had been rubbing on the carb housing. (I've corrected that.) Bad float? I know I'm getting spark to the spark plugs as I pulled #1 and laid it next to a ground and I am getting a spark.
Question #2 Any secrets to removing the final drive/rear axle housing? It appears the rear axle seal is leaking and I know the seal next to the transmission is leaking. Also, I suspect the brake shoes/drum are shot. I plan on replacing both sides.
Any suggestions would be helpful. Thanks

You could have the timing off 180 degrees.
Did you install a new manifold? Put a plug in the open hole 1/8" pipe plug. Don't ask me how I know about that one. I did that on my D14., could get it to start with much difficulty but it would only run wide open until I realized I didn't install a plug and it was sucking air.
Try removing the plugs and squirt gas into all of the cylinders, re-install the plugs and give it a spin. Could try a little ether too.
My D15 didn't want to start either, but a shot of ether 2 times got it running. LOL Bob

Gas can only get into the carburetor thru the float valve. Make sure that will shut off by blowing into the inlet while holding the carburetor level in your hands. (bad or no gasket under the head of the seat?) (needle float seat binding?)

Double check the TDC on compression stroke for timing by making sure both rocker arms are up on number one cylinder.

Choke plate closed on the carburetor will pull gas into the carburetor when cranking even if the float valve is working.

I did install a gasket under the float seat. I'll pull the carb and check it again for proper shutoff. That way I can recheck for a bad float, too. I did install a new manifold and the 1/4" plug. I've checked the timing twice but I'll do it again.

To make an engine to run you only need compression with the proper fuel air mixture and spark at the proper time.
If they do not run it is the cause of one or more of the above being missing.
A flooding carburetor can cause an improper air fuel mixture. Valves not being closed will cause a lack of compression.
Spark with one valve being open rather than both valves being closed will not cause combustion. This is when timing is 180? off or not firing on the compression stroke.

It is just a shot in the dark, but like Dick said compression is a possibility. Sometimes when we adjust the rocker arms, after an overhaul, we have them too tight, for the initial start, and gas doesn't get sucked up to the manifold. This can make you blame the carb.