my uncle has a 90 or 91 grand marquis. he is junking the car and getting a new one. would this block be an ideal candidate for an engine build? i would like to grab it and keep it for when i am ready to build one? are all 5.0 blocks the same from the factory?
It's a roller block but won't have the roller cam or lifters, but you can use a roller cam if you want to since the block will have the threaded holes for the "spider" and accept the same roller cam as your HO block has. It will have crappy E6 heads (I think) though. It's a good block to build on since it may not have been at WOT all its life I'd do it...
the last two years of the 5.0 in the vic's (90-91) were roller blocks with roller cams and mass air...in '92 they went 4.6. the blocks starting in '85 (E5TE, E6SE, E7TE, F1SE) were all pretty much identical...all iterations were used in H.O. engines for the Mustang, only difference being firing order, pistons for the H.O. were forged from 86-92...all the rest were either cast or hyper. you might find a roller block in some trucks that don't have the bolt anchors for the spider not drilled or tapped, but that's not a huge deal to get that done at a machine shop.
in a word, yes the block is ok to use up to the same hp levels as a so-called H.O. block.
that's how D.S.S. and CHP make all their "seasoned block" engines...they dont' have to be out of a 'stang to be a decent block...