quick question i am just starting to rebuild my cossie engine and want to check if i need to have a rebore and pistons as it slapped quite bad when cold the bore messures at 90.80 and the pistons at 90.60 its a 200 block with 2wd pistons i am aiming for 500 brake the spec of the engine is 7.4.2.1 cr ported polished head 25mm inlet 24 mm exhaust bd14 inlet bd10 exhaust isky valve springs long studded etc running a t4 and 83lb siemens do i need to change the spec and are the pistons ok to reuse?