pistons, rings, and bore sizes...

Spank - ring gap for us - 2 thou per inch of bore.
"racers clearance" on skirt = 6 thou and noisy as hell
that big a clearance gets you the wrist pin circlip issue so you gotta go buttons.
knurling is good on the loose pistons - for a while - they will hold more oil.

your bigger problem is the valve springs - you are suffering coil overheat it seems. have you looked around to see if ANYTHING else fits?
... otherwise I had great luck with my ghetto 1100 using Isky outers and old a/a inners without the inners spacers. Hard to find the isky's and everyone says they're crap. You need to machine the cap a bit to get them to work.

"knurled" for guides is different and a really good idea - it is actually "Rifled" as in the same technique as for gun rifling only more turns per foot/inch... I dunno how you'd do it in a backyard method.

There's a full albeit dated /old skool machine shop at Palomar JC. I took an automotive machining class and an engine rebuilding class and burned through a bunch of stuff to stick on my shelf and that I've pretty much used all up. Folks thought I was nuts for knurling (rifiling) removable guides, but it worked a treat and the school bought the knurler and reamer for me in the correct sizes. And knurling guides was free, replacing them cost $10-20 in parts.

I cut valves so thin you could shave with 'em. But the worked!

I did all of this with hand held tools-- the knurler was just a bit that attached to a hand held drill with a gear reduction device, and the reamer same thing. I didn't use the power tools to cut the seats-- just a hand cutter. The seats were/are all different depths, but I was in more control and able to only remove necessary material to clean 'em up. Used washers to shim the springs as needed.

Need to sign up for that class again.