First, Unless your engine builder has good reason to think your block has major main bearing saddle/cap alignment issues I'd stay with the block and get away from your engine builder, just my opinion. As Brent said, the block is not your enemy.
You didn't mention which
oil pan your running or if the rocker oiling is restricted. Both could cause oiling issues too. As Brent said, the only guaranteed way is dry sump or a 3 quart accusump. The accusump by far would be the least expensive option.