If you decide to (or need to) go to 0.060" over, PM me. I have a nice set of 10.25 to 1 Venolia Pistons with 0.990 pins and factory LY rods (bushed to 990 on the small end) that you can have for the cost of shipping. I built almost that exact same RB motor (MP 509 cam, ported Stage IV Heads, Rhodes Lifters, etc) back in 1987. They're all good parts that came out when the #2 bore got a hairline crack on the major thrust side. I'd sonic check your block before considering going 60 over. I'm finally getting around to "reblocking" this spare motor with a 0.030 RB block I picked up from a member here and I'm throwing Eagle Rods into it so the old pistons, pins and rods are all headed to eBay if you aren't interested. This stuff is pretty light so you'll have to rebalance with your crank. My machinist recommended I reuse the LY Rods with new bolts at the power level of this build but I decided to invest a little more in case I ever put better heads and a bigger cam on it.

Back in the day, I cut most of the lawns in my neighborhood so I know what that's like. I'll help pay it forward if your boys are interested in Mopars (none of my kids are). I just dug up a picture of the rods and pistons out of my pictures on paper from film archive so you can see the parts. The pistons have mild carbon buildup from maybe 2500 street miles but I assume that your kids can scrub These parts look fine.

And before anybody PMs me asking for the rods, I'm only extending this deal to "gss" and his boys.