Unless the bore looks scored or otherwise poor, I'd just put in a new piston and rings that are .50 over. That's the largest BS offered. If the piston looks decent, you can get by with just new rings. It would be pretty tough to adapt another brand of piston. You have to have one that has the right material ( there's a difference in piston aluminum composition for aluminum vs. cast iron cylinders), then the piston pin size, the ring locator pin position, the crown height and finally the amount of dome has to match or be compensated for.
For all you tinkerers & mechanics out there - Harbor Freight has their 6" digital calipers on sale for $9.99 with a coupon. The coupons are in HF ads in nearly all the current automotive and cycle magazines and the Sunday supplements in major newspapers. If you don't already have one and you're near a HF store, it's worth the trip. You can also use the coupon for mail order, I believe, and you can also get up to 7 or 9 at that price. Some of the coupons I've seen are good until November, some expire in August.