Borofloat high temp glass was intended for high temperature incan lamps. What you want is a UCL (ultra clear lens) from flashlightlens.com. It is its namesake, water white with an anti reflective coating to maximize light transmission by eliminating reflections, almost 10% more efficient than standard uncoated mineral glass. Top of the line for seven bucks or so.
Modamag makes his very good M2 reflector, also go check out Light-Edge.com they stock a full range of Mag reflectors. Fivemega's reflectors are top shelf, MM and FM can be found in group buys and passarounds. Actually, believe it or not for LED applications the stock Mag is superior to the textured ones, but if your taste calls for a smoother beam at the expense of throw then go to a MOP. Or even a HOP if you like big floodiness. Ive come full circle, went from mirror finishes (max throw but shows artifacts) to stippled and back to mirrors again. BTW, it drives me utterly bananas that folks spell it STRIPPLED (THERES NO R, NEVER WAS) or STIMPLED. (stip-pull) stippled reflectors give a very smooth and large center spot, they change profile more than MOP which tends to soften artifacts and change distribution less.
good luck, have fun!!!!