question about piston rings... ??

When installing new rings on an old set of pistons....
What are your thoughts on using one size over 
and using the proper tools to grind the proper
end gap?   Are the normally supplied rings the 
properly sized?   If the bore is just a big larger than
perfect, wouldn't an oversize ring allow the proper end gap
to be set?

Paul Tegler     ptegler@gouldfo.com    www.teglerizer.com