newish to me built 340 valiant feels sluggish. Timing?

I really appreciate all the help even if some is a bit over my head. I was a fuel injected import guy for years I know I know. So after reading I'm guessing my plan is to set the initial timing and play with the distributor settings a bit and possibly get rid of the vacuum advance, check compression just to be sure of the health of the motor, and get I'm thinking get rid of those e3 plugs the car came with. Any suggestions there? Lastly I've always wondered if that 670 has been holding me back so to speak. It runs great no stumbles nothing though. Oh I don't know if it matters but it also has a jegs 2800 stall converter. Crap or not? Thanks again!