Usually you subtract about 10 mm from the head diam for the reflector ID, could be higher to bout 12 mm or so. Some lights do it to maximize the reflector ID, some are notoriously bad about it, if you've seen those reflectors with the wide rim. The top end view pic in the OP looks average, not great -- I'd guess about 11-12 mm subtracted form the head diam. Usually you can go thinner with an SS bezel, then of course you got room to go wider with the reflector. Bugs the heck out of me when a so called thrower doesn't maximize the reflector ID.
That's sort of bad news - head diam is 69.5 mm, T30 is 70.0 mm, so if the reflector ID is 5 mm smaller than the T30, than you lose an extra 4.5 mm. The T30 though does appear to have a narrower SS bezel, shown here: http://www.acebeam.com/t30