Another opinion question

Ok I'm new here I've actually been reading alot of post for awhile and everybody seems to be noligable and real friendly. Not to mention a great place to get information about the car that I love.

This is another engine question becouse I only have enough money to do this once so I want to get it right. My altimate goal is to get my 73 Duster running well enough to beat most rustang's and rice burns. I'll start with what I have.
..904 trans with a 2500 stall
..8 3/4 rear end with 3:91 and a locker
..headman street headers 1 5/8 with duel exhaust

My thoughts were this take mopars 406 short block, use a set of eddy heads, and the performer intake I have. WHat I'd like to know is hwo much compression would this give me? Whats the differance in performance between a single pattern cam and a duel pattern and which one?

Lastly any ideas what kind of power that would make me and times I'd be looking at would be greatly apreciated.