Cool. Got some similar opinions on zilvia.

GTi-R Internals in S13 SR20DET? - Zilvia.net Forums

54c pistons in both (but remember my pistons have those sweet little dimples on them from the retard putting the rocker guides in backwards). Rods are thicker and rod and main bearings are 19mm versus 17mm, but rod and main caps are the same size, so from what I've read, the crank fits in both blocks.

Some guys claim GTiR oil pump is highest flowing SR oil pump... Just needs to have an additional hole tapped on top to attach it to the head and "allegedly" it fits. With the GTiR crank sprocket. Which I'd obviously have if I ran the GTiR crank.

Mostly seems to be the australian guys doing wacky stuff with GTiR/s13 hybrid motors. So I've been reading a bit on their forums about how to rig shit.