As far as GC goes...
The goal of the punch block series is to bring the attacker into stage one, where you are holding them tightly in your guard, leaving them no room to punch. (Overhook with head control) Stage two is when they bring one or both arms back to punch, which you immediately block with your shin, holding their tricep with your hand.
If they sit further back, you move to stage three, putting your knees near their chin and feet on their hips. Finally, if they stand right back up, your feet go on their hips, keeping them too far away to land a punch. As soon as they try to shove forward to get close, bring them back into stage one.
If they have stood up like in stage four, but either stepped back or simply not pressed forward, you need to shift your strategy. Now their weight is no longer driving into you, so instead you want to kick at their knees to get them to step back. This puts you in stage five, from which you can spin on your back with a foot raised, staying square to your opponent. (Allan Goes vs. Kazushi Sakuraba in Pride 4) ( Renzo vs. Oleg Taktarov)
How similar is this to Sperry's Vale Tudo style? They have a 5 day free trial so I guess thats plenty of time to watch all the punch block stuff...