I need advice on 425 rebuild.

1. Can I use any 4 bbl pistons OK. I know compression will slip from 10.5 to 10.25 to 1.
2. Are all 425 timing sets compatible - excluding the cam which is Torondado unique.
3. Does anyone have a economical source for pistons in .030 over?
4. Any other advice would be appreciated.
5. For those looking for a better deal on valve springs, 302 Ford makes a good interchange.

 

You must use Olds 425 pistons and are available from EGGE. 2 or 4bbl makes no difference.
All modern Olds V8 time-ing sets should work regardless of cam.
The 425 Toro uses larger lifters also available from EGGE.