Lyle,
I think that engine is very similar to the somewhat later K&B .61? Steel sleeve, aluminum piston, CI ring? You might search under K&B and find more info here on Stunthanger.
If it has ball bearings, so much the better. If it has one in the front, for sure it has one in the back....
I have never run one for control line, but rebuilt a K&B for a friend who did.
With that combination of sliding metal, I'd use at least 22 or even 25% oil and probably half of it castor. I'd probably start with 5% nitro, since that engine has got plenty of moxy to haul a good-sized plane. You can go check Randy's fuel suggestions in the article pinned at the top to see what he recommends.
Because of the metallurgy, the break-in routine is more old-school: light prop load, run it rich, lots of lubrication, don't let it overheat but you want the ring to wear in and seat. Start with a 4-stroke and work your way up to a middle 2-stroke as you put heat cycles on it. Don't run it hot and collapse the ring. Just guessing here, but for break-in, I'd be thinking about an 11x4 prop, maybe a 12x4.
I believe the engine I worked on came off of a Score, which was no lightweight. I don't think the K&B setup is as well understood as the ST.60, which seems to be the easiest of the era for most guys to run. Not sure what size venturi was in the engine I tore down. I don't see that listed in my notes. Sorry.
Dave