I am thinking about boring my 240z engine I have after pulling it apart and seeing piston number 3 is rusted and pitted but everything else seems to be fine. So my thought process is i could get it bored out to 90mm vs the 83 it has now and it would solve the pits on the sleeve problem. Does anyone know any good aftermarket flattop pistons and also oversized or just higher performance valves. and last but not least what am i getting in to if i want to do a bore on it do i have to change heads or can i keep everything else and be fine.

And I know some of this might sound stupid or pointless but just bare with me I am new into this Datsun stuff.

To get 90 pistons, you need a L28 block. You won't be able to machine your L24 to get that much bore.

90mm on L28 is doable, people on hybridz have done it many many times. Just look for L31 stroker to get more details about it. GEtting into bore modification will lead you to stroke modification, head modification, custom cam, induction change, ignition, etc, etc.

Good luck with your build. I haven't bored my block (only 0.30" to repair it) but I have done any other modifications and I love it

Look also on this board for engine build, there're tons of info to gather also.

Books such as "how to modify your Datsun OHC engine" and "How to Rebuilt Your Nissan/Datsun Ohc Engine" will help you a lot in the process.

I do have a 280z engine and 2 other engines including a short block I am starting to think i am just better off taking my old 280z engine and throwing all these parts on it.