option A sounds good. The crank should be fine unless your mains fecked up its been scored.
Hks pistons cost a bomb, why not cp or je ones?
Might as well get a full nissan gasket and seal kit then you can do your stem seals while your at it.
best to get the head skimmed while your at it too if running mhg.

How much boost are you planning on running? Standard internals are proven to be very capable at 1.4bar and some lads have run more on them.

Liners are the job when running when running silly boost or pistons over 87mm