I have run Both Clifford and Comp Cams. Never had a problem with any of them. Did have a cam go bad on a BB chevy once, can't win them all.
Yes you will hear a somewhat choppy idle and it will be around 750-800 rpm. Atleast 100 rpm higher than stock.
The Clifford will require the use of springs to match the lift and possible machining of the valve guides for smaller positive seals(also because of the lift. The spring can be bought from Clifford, I have a good one I use.
The 390 4 bbl will give better all around driving than a 500 2 bbl. Most of the time is spent driving on just the small primaries and only at full throttle will the secondaries open. Probably better economy also. Tom
