Got a cool new cruiser

Hello again,
I got a 77 stepside from my friends dad for 1500 bucks. Should b driving it soon. As usual I thought I would bug you with a few questions I have.
Well, the truck is in fair shape, and was being drivin daily for a while. It's a 305 with a 3 on the column.From what I am told about two years ago the carb was acting up. Since the drive train was all origional, my friends dad decided to put another motor in it. He had the 305 from his el camino sitting in the garage with a around 20000 miles on it so figured he would put it to good use. My friend installed the motor along with new long tube headers, a performer intake and an edelbrock carb. Not sure what size it is, hopefully the 500 or 600cfm. I am told the 305 has a stock rebuild done to it, so Im guessing dished pistons and all are still in use. I remember the el camino running well with no problems and no smoke though. Also included are aftermarket vital gauges, a tac, and a cool new hurst floor shifter.
I am wanting to drive this truck pretty often to keep the miles from stackin up on my z71. So this thing needs to be low maintanance and somewhat fuel efficient (for a truck). But I would also like to take advantage of any power that may be gained without hurting street ability and efficiency. I think a good cam choice should help out quite a bit. Im thinking of running the comp 260h high energy. What do you think? And Ill b running duel flows through 21/4 pipe. O, and can anyone give me any advise in switching to the floor shifter?

Thanks