I do not know if there is a "standard" thickness. There will be a bit of trial and error. I'd probably make 2 and run it. If it still overheats, or has other problems, add another.

As far as overhang tolerance, you want to avoid overhang inside the ccombustion chamber as much as possible. The whole "sliced fingers" thing is a bit scary, which is the reason I'm not sure if I could make them. I would be very tempted to spend the $$ on the OS part and hope it fits. If it does I'd get three or four total and start experimenting.