DBD what you have is perfectly acceptable. I think some guys here are over thinking it. Being the type of airplane it is I seriously doubt there will be any thrust adjustments made. Hell I see that on at least 50% of the aerobatic airplanes I see have never had a thrust angle adjustment and these guys want to anticipate one on a trainer. Lol. The only thing I would add is that if it is too close you could have some interference should the engine mounting screws work loose or you loose an engine bearing. In the end anything more then 1/32 would work just fine for your particular set up. Looks to be fantastic workmanship on the build from what I can see. Trimming a cowl causes some guys lots of greif, yours looks great.

Jaka, awesome looking Proud Bird, makes me want to go out and get one. I would of course have to bash it into a Rivets though. I hear those EF1 airplanes are great conversions with a good .32