I'll take a few of the leftover points --
As for your development of the 240 - I'm trying to remember what you have done. The GCR is very strict. I've heard a lot of people cry when the had to remove years of mods to start building to class rules. The best thing you can do is to buy a pre-built race car. In the long run, you will save more money than you'd ever imagine. I'm sure you could "bond" w/ a nice ITA SOHC car... it's all the things you love (and about the same power

LOL )
As for starting off driving in A vs. S, I think A is the winner there. ITS cars are generally faster than ITA cars. For that reason, ITA is a better place to hone your reactions (b/c things happen slower), a better place to hone your skills (b/c if you can keep momentum in a slow car, you can do it in a fast one), and - honestly - a better place to crash (b/c you aren't going as fast in many of the danger spots).
I just deleted a whole speil about what group might be easier to learn to race with b/c I think that's more important that in what class, but suffice it to say, I will get my SCCA license, then run mostly NASA events until I am comfortable racing w/ the big boys.
bbp - 155? OUCH! You have the pimpy Sunbelt motor, but are you at the edge of the rules in terms of build up (isn't there a fair bit left after SS)? I guessed you'd be able to get 165-170 out of a pro-built motor if properly set up. Any ideas for a custom built header? If Nissan doesn't have the equivolent of a Puckett or Hytech or SMSP or whatever, it needs it.
**edit* I gotta type faster -- I'm already OT

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