I ain't no 'spert, but those are older engines, and I would suggest somewhere in the vicinity of 25% castor, with 3-5% syn to help keep it "clean".
Also maybe a 1" shorter in dia prop so that you don't "load" the engine too much, and yes the same pitch as Fox (5"-6") pitch.
Glow plug try one with idle bar by installing it and SLOWLY turn the prop so that you will not have idle bar interefence.
Run it in like you would a Fox, somewhere in the area of 8200-8500 R P M, with adequate cool down between runs.
Hope that this helps...
