Howdy Scott:
Please reread the sticky on head swaps at the top of this forum. You will note that after '69 all 200 and 250 casting are the same.
If you're looking for the best head to upgrade, look for a casting of '76 and later. Good donors in the recycle yard are Mavericks/Comets, Fairmont/Zephr's, Mustangs/Capri's of '80 to '82, Granada's/Monarch's, and Bronco's.
Adios, David