My 2 cents.... .002 thousandths is about right I think for that size of bore. The gap can be more on larger dia rings. I still say for the price of a Boman ring...it is worth a try. So far every engine I hand cranked with a new boman ring had real good compression even before runing. The last 2 was a ZDZ 50 and a Webra 1.2. The Webra fom new did not have much compression at all....dykes ring. It sure has compression now!!! on that using 320 grit. I would not do it. Some grit can embed cyl wall in some cases. Then what happens is fast wear. Now it seems like if you place the ring in bore and measure the same .002 in many places....the bore must be close to round and plenty usable. Get that Bowman ring...and find out for yourself. Not much to loose. Capt,n