I believe both blocks are the same the difference
is the crankshaft, I have a 361 ford Ind. motor
when I had it rebuilt they said I could make it a 391 Ind. motor but the crank I had was a 361 so they worked that crank and I have a rebuilt 361.
It's in a 1977 ford, L 700.So depending on your crank, if its bad order a 390 or use what ever
you have. I think the through is longer. Hopes this helps
No, Im pretty sure you cant get 427 out of a 390. I read an article about it once in a magazine and they said the 427 has a huge bore, so if you tried to bore out a 390 to a 427 bore you would hit the water jacket. If you want a 427, you would have to find a block for it. 428 is possible though