Re: 351w horsepower gain help???
A number of years ago I helped a friend bring a full sized Bronco with a 351W to life. I think it was around the same year as yours.
We did it simple - Edelbrock Performer intake, 650 vac secondary Holley,l
matching Performer cam, "straight up" dual roller timing chain to get rid of
the factory retarded cam timing, headers, dual 2-1/2" exhaust with turbo mufflers.
We freed the engine from all the timing curve controls like the retard, etc.
He was AMAZED at the difference, and the improved mileage and towing ability.
Changing the cam IS "going inside the engine" to a small degree, but when
you're changing intake is a GREAT time to do that.
At the least, do the intake/carb/exhaust and distributor mods to start and
put on a straight up timing set. Even just that will really help.