New rings would require a fresh finish on the bores even if nothing but a glaze breaker or a ball hone is run through them.  Assuming the original rings are not worn, then I see no issue in reusing the same rings in the same bores.  Because the second ring is a tapered design, looking at the amount of wear on that particular ring is always a good indicator of how much wear is on the rings.

Lorena, Texas (South of Waco)

cos,
 I ran those Jahns  pistons too. Had the same experience and retired that engine. 3 7/8" bore.
I made a wax cast of the dome on my pistons and cc'd it. the result was 17 cc.
 Jahns also had "1/4 inch deflector" piston as they called them.
Hope this helps.



"FREE SAMPLE"

Thanks  Gaga  Exactly info I need.  Those lumps look big, will do math and see how much it  rises comp. ratio with g-head 69 cc (?). As mention above over 11 to 1 I suspect.. I cc some 471 heads i had redone for SC engine, they came out 78cc with .015  surface clean up. Guessing those  pistons must weigh 800 grams.

COS, are your Jahns pistons 3.875"? If so have you found rings for them? 
Thanks

"FREE SAMPLE"

Thanks  Pistons are .060 over 292 so 3.81?  Engine is still together since 1965. Has very few miles (1/4 at a time) but have not bore gauged cyl bore. Did pull cam out, was still perfect .290 lift S/C cam I bought in 65 over counter  ford dealer for less than $20.