Just refurbed one of these. Service manual calls for .035. That being said, I used an NGK BR6S and did have to open up the gap to .035. Don't know what is was, but have considered going down to .030 just to see what it does.
Out of curiosity, how much did he get? Too bad he didn't let you permanently borrow it. Oh, well.
I closed up the gap on the NGK to .030 and saw no difference on the tach. Gonna take it back to .035 tomorrow.
He got $40 out of it. The coil actually went bad on it, and he didn't want to put anymore money into it. He got about 20 years of good use out of it, so that's not bad. It seemed to run fine on 0.030", so I doubt there is much difference.