We put a Kenny's triple in a six speed with zero mods to the tranny or the arm. It was a 3200 plate load though.
The McCloud street twin is a good clutch, but will not handle alot of abuse.
The triple I put in last week required alot of fab work to get it to fit. Kenny is doing a new arm to make it a drop in for easy install. I will say it is an awesome clutch. We pulled it at the State fair on Monday, and will be at a couple of pulls this weekend as well as Scheid next weekend. I don't know why anyone would run a double disk after running these Kennys clutches. Both turned out very nice. The 4200 pound plate load diaphram cover is very easy to push, and the clutches separate very easy to allow gear changes with minimam drag.