Welcome to MAAST and SA. I have regular MH Reflectors and keep them off the canopy with a couple of washers which creates an air space and have never had any problems. The only question is how many fans do you have in this canopy to keep things cool?
Is your ballast a Ice Capp Ballast? If so you will need to purchase another one from them. Just remember the 440 and the 660 are wired different so you cannot use the same harness. If it is not Ice Cap then maybe there is some type of number or Nema configuration number listed on it?