WOW!

I've seen (and done) a lot of "oops" things but that's a first. Glad you figured it out!

Great job!

Use a marker on the side of the piston to mark the ring stops. I assume you dont have a propper ring compressor? A few tricks you can try if this is the case.remove the piston from the rod, place the cylinder on and pull rod up to top.reinstall piston on rod. Slowly turn crank to bottom ring,now you can both see and feel the position of the rings, just line up the mark and rotate the crank to the next ring. You can use popcicle sticks to push in on the rings. Make sure the markings on the rings face up
You posted the discovery as I wrote this, blah.
I have never seen that one before....woW
How in the hell did you flatten spring steel!

You're a brave man to admit that but thanks for posting & the pic too. There's always something new out there to catch us out. Nearest i came to that wasn't really self inflicted but my RD200 in a PE 250 frame had growling rough main bearings. As i stopped, one ball of the RH main rolled out through the balance hole in the crank wheel. Cage broken. Pushed the start button & it went solid. Conrod big end hit the ball-- & bump!! stop. Hope yours survives the damage. Takes more than that to stop an RT1--think ya said RT1.

I've seen and done worse.

Just offering my 2 cents worth on gaskets. Use Yamaha OEM cylinder base gaskets. Some aftermarket base gaskets are too thick. This will allow the head bolts to loosen with expansion and contraction as the engine heats up and cools down.

Had trouble with my two RT3 regular riders that someone else restored with aftermarket gaskets.