short of a turbo or supercharger, you'd need to do more than just cams to get noticable improvements (number wise) on that engine.

to ring gobs of horse power from a normal engine, you really need to build up one just short of a "racing engine". I'm talking intake improvements, exhaust system, cams and springs, larger displacement, blueprinting the engine and so on. In other words you need to buld a system.

The downside is that to gain the additional horse poswer you need to raise the RPMs this cuts the reliablity and life of the engine by increasing the stress and heat of that engine.

This is why so many manufactures used turbos and superchargers to accomplish vast horse power increases. How many 426/425 hp hemis of 1969 do you see with 150,000 miles on them ..

My point is that they produce gobs of HP but had pretty short lives, or 10,000 miles a quarter mile at a time.