Georg,
You can put any type of clutch in front of a Lenco that they make an input shaft for. You need to pick a clutch for whatever you're mostly using the car for. If street, you need a street clutch, if street/strip, or strip only, pick a clutch designed for your HP and car weight. The CS1 and CS2 will take anything you can throw at it, up to 3000HP for the CS1. The CS2 is a slightly smaller case if you have space limitations but will still handle 2500hp. The ST1200 is just that, a street version thats rated at 1200hp. They use aluminum cases instead of mag like the race versions and 8620 material for the gears instead of 9310. The 8620 is the same material used in most ring and pinions and is a little harder for better wear on the street. Thats how Lenco can get the cost down a little for the street version. One thing to consider is heat buildup with the Lenco if you are doing a lot of cruising, I know my CS2 doesn't have any provisions for fluid cooling although the ST1200 might. BTW, I'm running a Bruno convertor drive in my altered and honestly think it would be streetable if I were to put it in a bodied car. You might want to look at a Lencodrive also, roughly same size as a glide in 2-speed configuration but you have the flexibility of adding more standard CS2 sections to it to make a 3-4 or even 5-speed. All it takes is dollars.....