It's all about what rpm you intend to use the engine at and how much the vehicle weights. When you go racing you want to shave weight off the vehicle and move the power band up because you need that torque at the high rpms to go fast. You want the maximum pressure in the cylinders at those high rpms. You don't care that about the cylinder pressure loss you will be creating at the low rpm range because you will never be below 2000 rpms.
An aftermarket camshaft moves the power band around the rpm range.
The higher duration of the cam the more cylinder pressure you will lose at those lower rpms. You're sacrificing the compression at the lower rpms for increased power at the higher rpms. Ford knew what they were doing when they deigned the original camshaft. It was designed to produce the maximum torque at an rpm that would produce the greatest fuel economy and engine longevity. And we have to remember it's a very small V8 engine with very little horsepower, it's not a small block Chevy with extra low rpm torque to spare that we can sacrifice for a good sounding camshaft.
If you have ever read a camshaft manufacturers recommendation for a "hot" camshaft it will say the camshaft is only suitable for a light cars like roadsters with high compression heads and big cubic engines. Th\at is because camshaft won't produce as much torque as a stock camshaft at normal driving rpms. A heavy vehicle needs all the torque it can to get it moving when the light turns green so this would not make a pleasna vehicle to drive at low rpms. Even in a lite roadster it would need higher compression and more cubic engines, to compensate for the low-end torque lost with a big camshaft so it can be comfortably street driven. That is why a big camshaft will always tell you need more compression and more cubic engines to make it work right.
The problem is the "wow" factor. It's hard to not fall in love with the sound of lumpy-lump camshaft like an Isky 400 JR, Clay Smith 272, Potvin Super 3/8th..., And they can be perfectly street driven in a light vehicle, you just need to remember they will not pull as hard as a stock camshaft at lower rpms. My dad's roadster I inherited has an Isky Max #1 in an 8BA. The first time I drove it I could not believe how hard that little flathead pulled street driving. But it has no lope to it at idle which is real disappointing. Even though I know that lope is the sound of a flathead with pneumonia at idle. I have about a dozen big camshafts, and I'll probably stick one of them in there and it will sound great, but I bet it will never pull as hard between lights as it does now.
