The 390 "GT" engine had the same camshaft from the factory as the 428CJ,,heads were of the C8AE-H variety,,,nothing special,,just drilled for the 14-bolt exhaust pattern,,,blocks were garden variety with flat-top pistons to give around 1o.5:1 compression. Full size car blocks are the same,,,but the better 390 blocks to get are the truck blocks with the ribs down the outside of the block,,,i believe they have a D4TE casting,,cranks are generic,,,but put a 428 crank and rods in a 390,,and that takes it to 410 cubes,,kinda stroker.Thats what i have in my 69 S-code Mach.Buy the Edelbrock aluminum heads from Jegs,,,bolt them on out of the box,,with a alum. intake too,,and either headers,or 428 CJ exhaust manifolds and a hot cam and electronic ignition with a 3:25 Posi gear,,and you will have one hell of a powerhouse.Just BE SURE to drill the oil passage in the block from the pump to filter adaptor to at least3/8 or bigger,,,this hole is only 1/4 inches,,and is the reason a FE wont last at high revs,,,also #1 main bearing doesn't line up it's oil hole on the block side,,you have to chamfer that gallery hole a little to make it line up.ALL those FE's were like that from the factory.Hope this helps. Jeff K.
Professionally restoring 65-73 Mustangs,,Full-size Fords,,,AND 67-81 General Motors Firebird,,,Trans-Am.Located in Simpsonville Ky.,Shelby County.25 years experience,,,,,with emphasis on building beautiful and unusual musclecars,,to include full-size too.Advice and questions are always welcome. (502) 338-1218 Thanks.