Farmall 504 gas engine swap?

My choise would be an engine from a 300 or 350, you would be getting a sleeved engine. You would have to modify the governor as all but 350 utility did not turn as fast as 504 does for standard pto speed. However if you get that 300 or 350 engine up to 2200 rpm you will have more power that 340, 504 or 544.

Years ago I bought a farm with a newly rebuilt 504, previous owner said he never liked the tractor as well as 300 he traded on it. At the time I already owned a Farmall 300 and one of these tractors were going for sale. I took them to field one day, had a No. 60 3x16 trailer plow. My 300 had more than a few hours on it at time. It was on it's 4th set of pistons and sleeves. The 300 out performed the 504 in every way that day. It had better traction, better power, better hydraulics, etc. The 504 went down the road. I think with a 300 or 350 engine you would have one heck of a tractor.