The 125 and 250 engines may have had a high CR but the TSS350 CR was actually very low. The reason for this was that it simply wasn't possible to bump start the engines with a higher compression, the rear wheel would just skid. I found the same problem with the Metralla - even in a high gear the 370 would just drag the tire. But even disregarding this problem it'd make sense to use a moderate figure - the heat and detonation tendencies would be a couple of reasons.
I think I've mentioned this before, but CRs with two-strokes are a game of diminishing returns. Every time you try to get an increase in torque by raising compression you lose some of it due to the decrease in EGT and pipe effectiveness. Not only that, but with a big oversquare engine like the 350 Buls there are greater heat losses with the big chamber and piston. As it turns out there isn't a hell of a lot of difference power-wise between say 9.5 or 10:1 and say 12:1. For a 350 Bul (especially on gas, and especially if you want to raise the rpm band) then a conservative figure will give good results.
As for clutches, the stock steel plates can take a fair bit of abuse. The type of oil you use has an effect on their torque capacity too. Depending on the material used composition plates may or may not survive running dry. I have no experience with the Bandido clutch but they look very similar to the Pursang style, only a bit bigger. Whatever plates you use you really need to consider them as a consumable item - even with the two step I imagine you'll be doing some practice starts to get your off-the-line technique sorted, and the launches themselves will be pretty hard on the clutch. I did some testing of different plates and oils some time ago; I'll post my notes if I can find them.