67 upgrades for 2011

[my67c20]

I have a 67 C20 with a 383 (450hp, 375tq) with a sm465, 4:56 gears non posi sitting on 16.5 8 luggers. I want to take it the track. Don't want to be that guy that does a burnout sideways and then miss a gear as i am shfting the trans. So i feel it is time to do some upgrades to the drive train.

Budget is about 2k (that the wife knows about)

Which automatic would be the best bang for the buck?
Scale of 1 to 5 how easy of an upgrade?
What year would be best to get a posi and maintain the same rear gear?
Would like to upgrade to a roller cam (older block) yes or no?

I have searched but nothing in one place. Any thoughts. Thanks