ive been told by a good source (a 3000gt owner and enthusiest) that he replaced 1 rod and piston on his 3000gt engine using a standard 2nd hand magna rod and piston.
and yes id say the pajero crank is forged.
and im unsure if the 3000gt heads flow better i havnt had a set in my hands yet but i do have some grandeur dohc heads and just going from photos theyre very similar.
and yeah depending on compression ratio most magna motors will take 6-7 psi without breaking immedietly