I put one of these on my 460. Runs pretty well. Haven't had much time on it since, but its been getting better each time it gets run. Here's what I figured out from the numbers:
Bore up 2MM to 54MM - Same as MS660
Displacement goes up to 82.4 CC - Gain of 5.9 CC's, about 2.5 CC's less than MS650
And yes, it is simple. I threw it on while watching a movie.