5/64 & 1/16th ring and max bore size

the engine that I have is at the machine shop.I bought the engine from Blue print engine, and they put 1/16th rings in a 5/64th groove KB pistions with no spacers.I've had the engine for almost a year and I have more drive time on my lawn mower than this engine,right now I have a ASE certified master Machinist looking at it and each day the price to repair is going up & up.
He tells me that the block can be bored 60th's over but I always believed that on small blocks that most it could be bore was 40th's

I'm gun shy on what to do because of all the issues that I have WITH THIS ENGINE.if anybody has had good or bad issue with blue print let me know please

Thanks for all of your input I really does me under stand better.
Alan