WOW! was that the understatement of the year LOL.
I do see why they don't allow the aftermarket block though and its because they want to keep guys from building the big motors, thus, forcing the guys who can't afford 2-3 motors per season to use 350 blocks and those who can afford several motors per season to use the weakest SBC block made. I guess their view is if your dumb enough to spend the money to build a big motor with a stock block, shame on you.
If they would just put a displacement rule in, say 410ci or so, then I don't see any reason for the stock block rule AND everyone would have bigger faster longer lasting motors.
JMO