I've decided to put the original engine back in my rs.. it's been out for about 10 years while I've had the zetec in.
I pulled it apart to inspect, and two of the bores have rusted and pitted quite badly. It was 40 thou over, at just under 60 thou there is still some pitting about halfway down the bore about a 1in long section. This is where the piston was sitting in storage.
Is it safe to go to either 80 thou or 93mm on a standard (not 200/205) block?
It will be a mild tune.
I've searched quite a bit, and some say it's ok but a bit unsure myself. I guess the other options are to get it sleeved, or live the pitting and get it bored to 60 thou. I'm going to go see an engine builder this week, thought I'd get some advice here first.
I want to keep this block as its the matching number.
Cheers
Andrew

Hi Andrew , the biggest size piston to safely go into a pinto is 93mm , maybe 93.5mm if the block is in really good shape. There is pistons to suit for sale in USA cheaper than UK , being for the cologne v6 2.8. You might need to buy all 6 in the set but it's still cheaper .
Once you've got the 93mm pistons the block will need decking about 0.040th to bring the pistons to the top. ..or do what i done and get the crank offset as much as possible and then get the block decked. Mine became a 2176cc with the above done and with some decent head work it had 116kw at wheels on twin 40 webers..

If you're unsure or want the piece of mind, have the block sonic tested.
 
As marty said, 93mm is 'usually' fine.
 
SHaun.

Thanks. I might get it sonic tested just for piece of mind.
If I go to 93mm can I still get it sleeved later (when it's time again for a rebore)?
Going to see an engine builder, just want to make sure I know as much as possible first!