I'm in the process of (slowly...) building a T-60 myself ([link=http://www.rcuniverse.com/forum/m_4997091/anchors_4997091/mpage_1/key_/anchor/tm.htm#4997091]see my build thread[/link]) and am building it with an inverted and cowled Saito .82
I believe that this will be an adequate engine, but if I hadn't received the engine for the price I paid and had to buy an engine outright, I would probably have gone with either the Saito or OS .91. I know several flyers who use Magnums with no complaints. The Saito 100 is probably more then necessary for the T-60 and I personally see no value whatsoever to paying extra for the GK. In fact, they wind up looking terrible when the black starts coming off the case...