hey, i was wondering are the P90 head, and N42 block used in any other engines except the L28ET? and is the P90 compatible with other blocks? sorry if these questions are noob, please put me out of my misery and inform me .

as far as I know here in the states the p-90 was used only on the turbo engines F-54s Don't know about the N-42

all L-series heads are compatible with all L-series blocks. if the head is from a bigger displacement block than what it's going on, you may need to notch the block. but otherwise it's swap-n-go