I'm 95% sure they're the folks I got my FRONT Mk. 3 iso conversion kit from (and a Mk. 3 front mount, rather than machining my Mk. I one down) and they worked fine. Something of a biotch installing (thought I was gonna need a frame spreader to spread the front down tubes, but I surprised myself somehow), but I don't think that had anything to do with the parts.
My general impression of Commando Specialties, whom I've bought a fair number of parts from, is their prices are slightly high but not outrageous and the quality of the parts is good. You can, if patient, save a few bucks by timing their ebay auctions, which it appears is what you're doing.
I'd compare a few of the other usual suspects - Old Britts, Fair Spares, etc. - and if these look like a bargain, buy 'em.
Good luck. Would be interested in your installation experience, as I have not done the rear ISOs on mine yet and probably should.