Let me offer my personal experiences.
1. Awesome move on a cam swap. However, before you go installing it, are you dead set on the VS cam? I don't intend to soud like a negative nancy, but the vs cam doesn't offer much of a gain compared to the XP or NIC cam. I mean, if you already have it, and can't return or don't want to sell it and get something else, I respect that.
2. Ls6 springs are fine, but same thing. If you already bought them, keep them. I not I suggest the crow 105's or L76 springs. They're not progressive like LS6's and it'll be less stress on your timing chain/valvetrain.
3. Double roller isn't really needed for a vs or xp cam. Xp guys usually bump the idle a wee bit just to keep the little increase in idle abuse to the chain down. Obviously I'd buy a new gm chain for peice of mind. You could buy a double roller if you reallllly wanted to spend the extra coin, but if you can't have a machine shop match the chamfer of the stock crank gear to the double roller, don't bother getting it. It'll cause more problems then it's worth not doing it. Even if you did the poor excuse mods like double timing cover gaskets and machined cover, it's not fixing the cause of the rubbing problem.
4. As for trans mods. If you need one, do it right the first time and get a TEP trans with all the goodies. I doubt you'll need most of it at this power level, but I'm sure you won't stop here, and you'll have more mods in the future. Yeah it sucks to drop 2-3k on a trans, but when built and driven right you should have years of trouble free driving.
5. I hate to come off as a douche again, but you won't be close to 300whp with those mods. Maybe 250-260whp with some other mods, so personally a stock trans with a cooler and a shift kit might actually work for you if it's in good shape.
