As far as manual transmissions go you have a few choices. T-56 6speed, TR6060 6speed (GT500 tranny), or TKO500, TKO600.
The T-56 is a nice street tranny that will hold up to more punishment than a 3650.
Another option is the 3650 tranny with an upgraded input shaft. It takes it to a fine spline set up which requires a different clutch package, but really makes the tranny stout. The 3650's have been holding up to high hp pretty well from what I've seen. I've been running around 500rwhp for almost 2 years trouble free.