Sounds like a solid warranty voider and car life killer.....
It won't hurt your car unless you use the extra power to go out, lose control and hit a tree. But yeah, crack open the top end for changes like this and the first victim is your warranty.
The real problem with doing aggressive cams in this motor is found in the cost/benefit ......... 4 cams make the job more expensive than engines with a single cam shaft and really Ford has given you 420HP in a small 302 cubic inch platform.
We've come a LONG, LONG , LONG way from the days when it was a really HOT PACKAGE that could achieve an honest 1 HP from each cubic inch of motor. 32 valves was once consider super exotic HIGH DOLLAR stuff.....today it's grocery getter production.
But really .......the older engines can benefit greatly from a cam swap. Depending on what you're looking to get......you can get wild sounding engines at idle no Coyote will ever match for "SEXY" sounding.... or maybe you're looking to optimize low end torque in a heavy truck and you'll usually get smooth a glass idle.......but don't ever discount the cam swap. It's probably the single most important determining factor you MUST GET RIGHT in the combination considered for optimizing any engine for it's application.
I've seen incorrect cam swaps make a DOG out of what looked good on paper......and I've seen emission choked motors optimized to beat the tail pipe test gain as much as 50-75HP with nothing more than a cam shaft swap that ignored the emissions test and focused solely on power.
A really popular trend is seen in the "top end" power combinations pre-determined by companies like Edlebrock to match up the correct heads, cam and intake...and they'll tailor these combos for specific engine displacement and compression ratio. They'll even tell you what carb size to go with too ....... the demand for these pre-designed and packed kits came from the number of people who'd tried and failed miserably to get their combinations right on their own.