I don't see why anyone would futz with a Gen I anymore when the LSx is so much more bang for the buck.
Then again, those crate sbcs are pretty attractively priced.
Once you get up there in terms of power, the cost, block strength, and head design starts to favor the SBC/BBC combos again, especially when you have options like the 15/18°, splayed valve, SB2.2 and SBX heads.