McCormick, IH machines do a good job as well.
Parts are very common, across alof of machines (having a parts machine is handy) - although the self-proplled models usually had a heavier elevator chain. Here is a break down.
91 /93/203 are self-propelled. All separation parts, and most hood parts and elevator chains, bearings are the same, or supercede to the 80/82 models.
Auger platforms, no canvas. Windrow pick up units from any of the abovementioned, fit all.
They made alot of all 5 of these. Good, simple machines, uses standard v-belts. Only PIA part is the rock trap - hard to clean, a vacuum is best. Clean it often - no one else does, lol.
The 64 and 76 (and earlier) pull-types had canvas aprons, yet the chaffers and shoe sieves (not the straw walkers) are the same as in the 91,93,80,82 AND the 203 self propelled machines. Larger elevator
chains on the 203.
Technically, if you were very bored/had the itch, you can put either a #25 or a #227/228 corn head on the pull-types. However, a #25 corn head is a heavy, heavy beast whch may exceed the frame strength of
the pull types. Also, they are slightly offset, to fit the SP machines, so will interfere with your PTO drive.
The feeder house, and drives on these heads are the same as the 80/82 , 91/93/203 machines.
You can do corn with the self propelled simple enough, but these pull type - machines were designed with small grains and rice in mind.
The JD or the All-crop would be the best if you dream of combining corn. Pretty common, in the antique world. The corn head, is the hard part to find for either. I dont see very many for sale.
You can also find a test-plot combine. Many, many manufactures across the ages, and sized for testing - or in your case, 2-5 acres. May be actauly TOO small, but i have not ran one, so cant really speak to
how long it takes to do an acre.
I can zip thru beans, oats and wheat pretty OK with my old IH herd, lol. Couple acres an hour, but i take my time, as i enjoy the ride.
Best of luck in your search.