Alphabettispaghetti
Club Member
I've heard a few times that the P30 shouldn't be taken beyond 86, but this thread shows Nissan used to take them out to near 88 for racing porpoises.
https://zclub.net/community/index.php?threads/l-series-capacity-increases.19808/
So, as long as your block isn't full of rust I think you're safe to 86mm bore. Which will get you to about 2.6L. Are you going to use the original crank?
Kameari say the early p30 blocks take 3mm over with ease. Not totally clued up on all the block changes though.