Swapping to a milder cam doesn't involve a rebuild- - - -I can do it in 4-5 hours in a running vehicle, quicker if it's out of the car and on an engine stand. For a little better performance without killing all the low end grunt, I'd suggest the Comp Cams 268-H and a set of their matching lifters. That cam was still pulling strong on several dyno runs we did on a 350 with rams' horn exhaust manifolds and a Quadrajet in the 6500-7K RPM range and it had a good idle and impressive midrange power. That engine was in a fairly heavy-bodied Chevy Monte Carlo. The kid who owned it ate 5.0 Mustangs for lunch at stoplights on a pretty regular basis.
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!