Putting in new motor

I am installing a new motor (chevy 454) The motor is being built to the specifications I request. I would like some guidance about the type of cam and intake manifold I can use. I want it to be better than stock. Should I be looking for alot of torque or a lot of horsepower? I live in it 60-70% of the time and it stays parked about 3-5 months at a time, but when I go to my next project it can be anywhere from Miami(currently) to El Paso(in March) then to New York. I want a good strong engine to pull 33 ft. with confidence.
Another question I have is about my generator; (onan 6.5) It starts and runs, but a little rough. When I turn on the A/C it boggs down and stumbles for a few minutes (pretty rough) then eventually stalls. I had it serviced about 2 months ago and it ran great until a couple of days ago. I put in new plugs and checked the fuel filter. Is there anything else I should check before I take it to someone.

Thank you all in advance
Re: Putting in new motor

As far as the motor, you need torque to tow with. I rebuilt a 1974, GM 402 big block police interceptor motor and installed it in my 1979 1/2 ton GMC. The ONLY thing that was not stock was the Torque Cam. That thing had so much power, I did not hook up the passing gear cable to the transmission. Every time the 4 barrel would kick in, your neck would snap back. Blew away all the hot shot Fords that were around then. Wish I still had that truck.......

On the generator, sounds like bad gas, or carburetor problems.
Re: Putting in new motor

its an 85 holday rambler imperial 33. I know its an old rv but we love it. It is a long and expensive story but we are committed to it.
Re: Putting in new motor

Your carb. is probably a Rochester. They were pretty good themselves, but Holley made a good one also. I don't remember what transmission they used.