Ive built, and ran the 3 mentioned here. What al is saying about cylinder support in the indy is the same we've seen, and the sleeves move around, and power suffers. They seem to be ok at 1000hp if the bore is no bigger than 4.53. More bore, or more power, and it starts. Also better bush the lifters.

The world has the weakest web of all.

The KB is the toughest by far, and the best oiling as made, but you still need to work on it.

Repairing the paper thin sleeve supports we've done several times by milling out the whole thing, and welding a plate in so you're welding on the ends where it's thick, then boring the sleeve holes again. Trying to weld up between, or on the fronts is a crap shoot as to whether or not it'll hold.