Engine: GSR 100%stock, If it matters goal is about 450whp

Planning this winter for pistons and rods. Is it ok to do A or is B the better one?

A-- 81mm pistons with a hone

B-- 81.5mm pistons with boring the block


Also forgot do I need a block guard need?

 

Bore to 81.5mm do it right


I ran a stock sleeved block with pistons and rods and a block guard, went 10.40s . I never really liked block guards but it seemed to work fine for me.