2.5 motor rebuild - advice needed

[ber911]

I am currently rebuilding my motor which was a 2.0 but has 90mm RS pistons and sleeves. I have a twin plug setup and would therefore like to build it with a c.r of 10.5:1. In addition if possible I would like to keep to under 2500cc for tarmac rally's. The correct solution would be to use 89mm mahle p/c - but this is too costly for me.
The two choices I am left with are to use 90mm high comp J.E pistons in my Nickasil cylinders and run in a higher class or 89mm high comp J.E pistons in sleeved cylinders. I dont have any experience with sleeved cylinders and am a bit hesitant to go that route even though it would put me in the correct under 2.5 class.
Anybody have any experience and advice for me?

P.S the car will be used as a fun road car as well as trackdays and tarmac rally's.

Robert