Thank you for that i wasn't aware of those differences which I believe don't affect the actual size of the unit that the subframe connects to. Im probably going to just buy the frame for the 1920/757c as a base and fab up from there. They have available some different brackets if I need to. Pricing most of the parts from Messick comes approx $3k without shipping so ill start with the frame 1st.One of the differences between the old Woods 750 and later 7500 models is that they went from a single-cylinder chain-type boom swing to a 2-cyl system. Buckets and prob even subframes should work on both.
My own clone hoe (Prairie Dog 7.5) is a beefed up 7500.
Those older 1720/1920 Ford/NH tractors really do need to be protected from breaking in half.