Ringed engine?

Older engines required far more breakin than ones today. They also weren't as accurately made as today. They also evolved using castor oil based fuel. We often had to run them an hour or a couple of hours to break get them reliable enough to fly. I'm not really sure it that engine is old enough to have all those characteristics, but I'd bet on it having some. The metal in older engines took awhile to break in. You had to basically wear the tolerances down where they were too close. And there were more of those places. And the metal was meant to last, not wear down fast.

Needle valve adjustment being very wide would be expected if the needle threads are very fine, or the needle taper very fine. If not, then the engine is having a draw problem. Are you running muffler pressure? Tank close to the engine? All the usual questions about tanks, plumbing........