Looking for opinions on pistons and cylinder condition

[ampzip]

An update on my comedy of errors.

Somehow I didn't realize to check if the engine had been bored previously. It had been already once before, so I decided to just hone it and install the new pistons and rings since previous ones were quite wore.

Finally got the parts and installed first cylinder fine. Was fitting piston into the cylinder for the second one and somehow snapped one of the piston rings...

Part numbers were identical on the boxes, both said 25 over. I'm only learning now (manual says nothing about it) that OEM rings need to be gapped?  What is a safe way to do this?

Edit: and maybe dumb question, but could I use one of the old rings in the bottom temporarily?

[1976RD400C]

It looks like the ring in the picture is for the next oversize bore size. How do the pistons fit in the bores without any rings on? You should check that first. Use a .002"-.005" feeler gauge alongside of the pistons to get an idea what's going on.

[ampzip]

Well upon closer inspection, I noticed there is faint numbers on the rings... they are in fact 50 over rings. Unreal. I don't know which seller to go after as both boxes are identical, only the rings were different. Guess I'm just SOL on those.

As far as the piston in the bores, I can barely get .003 to fit.

[m in sc]

its actually comon to file down one size set over to get a perfect gap. so, kind of a blessing. t have trimmed them using a fiber cotton wheel in a dremel, fixtured, and taking small increments off the side. do one side, then the other to make it even. be warned, it does FAST