I always wanted to put a nice set of cams in mine to get some more power, but last time I checked all 4 cams were around 1200 which I didnt have laying around. So That Idea died fast. If you just want to hear some lope like it has a cam, try maybe going with a throatier exhaust. Maybe kill the 3rd cat and ad magnaflows. I know I have a slight exhaust leak and I can actually hear a hint of a lope from it. I bet with a fairly free flowing exhaust youll have the sound.
Also you cant run a gear drive on a 4.6 DOHC, The over head cams are driven by a timing chain and gears, where as a conventional pushrod V8 used a short timing chain and a pair of gears to run it. So you could fit in a gear drive kit. On a 4.6 the kit would have to be pretty huge.
What are you intentions with the car? If youre looking for a cruiser, I bet you could rebuild the heads with bigger valves and cut the stems for flow, then just clean the ports up but dont make them bigger, then port match, your imrc's, your upper manifold, throttle body, and exhaust manifolds. You should actually boost port velocity and have a much snappier motor. Then do the steering column mod and switch to cobra manifolds so you can ditch the upper manifold cats, and remove the 3rd cat. You can install the 4.6 DOHC Cobra cams, Cobra MAF, bigger injectors, and then get a custome tune. The car would probably really feel good.
Thats kind of what I am saving up to do right now. Eventually I will, I just dont want to pull the heads off a mark with the motor in the car it looks like hell...
The plan comes from what I did to My Cutlass. I swapped a stock low mileage 77 Olds 403 motor into a 86 Cutlass Supreme. It was quick but not great. I picked up some higher compression heads, and a Comp Cams 268 cam and it got faster but it wasnt great. Then I pulled the same heads back off had big block valves installed and had the stems cut like I told you and the thing is a tire burning machine and pulls hard up to redline.... As far as a tune I kept the computer controlled distributor and carb and changed the tune and recurved the distributor. So basically were applying the same principals to the mark. Im not sure what it comes out to in Dyno Numbers but from the Ass dyno it felt very significant.......