Repeat for emphasis...
IF whoever does your boring/plating does NOT want the piston that's going in the bike,
find someone else to do the work!
There is no reason to approach the fit from a 'one size fits all' point of view. You aren't trying to put together a bike for every man, but YOUR bike with YOUR parts.
That's one thing that's nice about pro-x and the 200 piston choices they supply. Unfortunately, that point doesn't apply to you.....
Rings aren't there to 'take up space' btw. Piston to cylinder fit is critical ..especially in a 2-smoke. Somehow figuring to substitute a ring fit for a piston NON-fit is a non-sequitur....an oxymoron.
Who's doing the plating? Consider langcourt as a possiblity. I haven't dealt with them personally.....just aware they are a choice.
http://www.langcourt.com/
And they're even in canada!!! In BC even!!!
Cheers!