TJ-
I went the other way, Kinda.
Gen V block. Had #8 piston grenade and windowed the block. The block was set up for roller lifters, and dogbones, and no fuel pump boss, either. BUT it was a flat tappet cam. Factory from 1995 or so. Indmar Marine, I think.
Located a block. It was a Gen VI (6) (1998?). I used the same crank. It too was set up for roller cam. I used a Comp cams flat tappet cam (for a Mk IV) and double roller timing chain. The Gen VI timing cover has 6 bolts and a spaghetti gasket, and I used a GM factory piece, its cast aluminum.
I had to 'Clearance' the inside ribs on the T/C for the timing chain, and make a plate to block off the crank position sensor, and notched the 4 pt front mount as well. A cam button was not used. I don't know the limit on lobe lift for dogbones, But I bet you'll find out. I know .540" valve lift is a crate motor. .632" Hyd Roller in a ZZ572/620hp, but its a tall deck, and no clue as to what lifter style it uses- link or dogbones.
