A short deck might be nice for huge budget builders but again they are a very small part of the potential market. The best volume seller is going to be hands down a std deck height, most bracket and street racers are going big cube strokers because it is so easy even in a stock block and the problem is a stock block can EASY swallow 4.25 inch strokes (440ish CID) then bolt on some 1/2 decent victor-W8-W9... and you will break the block, maybe the decks could be cast with enough extra meat to lop off 1/2 inch if you have unlimited budgets and want or need a short stroke high RPM deal. They would not have to actually machine and sell short deck blocks but the block could be turned into one if so desired by the guys who can afford to actually do those type engines. As for main bearing size do it in std 340 size, a 360 crank can be turned down but not the other way around and the rich guys can figure out a way to run smaller journals (bearing spacers, weld up re-machine) if the rest of the block fits their needs. The only two things I personally would want that a lot of guys may not apreciate is siamese bores and head bolts anchored way down low to spread the clamping load better across the deck but I could live without either, if I got both for $3000 in a "check and run" condition I would buy one in a heart beat.