reason i am asking this is wonding if it would be worth it i found a combo for cheap from a buddy for gsr eagle rods and 84mm cp pistons and i got a b20 block but cant aford to sleeve a gsr block to go with the 84mm pistons so would it be worth geting this combo and using a gsr crank in a b20 block? its also a boosted setup

 

You can do that, yes, but the siamesed B20 bores are notoriously weak. Some people have good results but it's a diceroll.

IMO it sounds like you still have a GSR block. Sell the 84mm slugs and buy 81.5mm ones and prepare to make a lot more power with reliability.