440 cam selection question

Have a look at the Mopar purple shafts on the Mancini website.
Mopar Performance ''Purple Shaft'' Camshaft Kit

I agree with everything RustyRatRod already said. With that 2X4 intake manifold and heads combination indicates this is clearly a throwback street showcar. More show than go as compared to current engine technology standards. No disrespect intended. A fun car that will attract a lot of attention from onlookers, but won't be an incentive for the driver to be foolish and to attract the attention of the local police. A fun car with 350 honest hp which is plently to keep anyone entertained on an evening cruise with the spouse and kids.

The most important thing to keep any flat tappet camshaft alive with be doing a proper break in procedure. After that you can reasonably expect it to last as long as you have the car.

FYI, the pistons you have are almost certainly clearanced for valve lifts of .550 at least. So you could go a little bit bigger on the cam, if you put in different valve springs. Though that would just hurt the driveability of the car, with only a relatively small gain in HP at the RPM redline.

Lastly, I'll comment on the stock connecting rods. They were built strong enough to easily rev to 6,500 rpm and live. But they are also at least 50 years old, and undoubtedly have many millions of cycles on them. There is no way to know how fatigued they are and how much abuse they will take today. So it is better for the engine to use a small cam, with a big torque curve down low and keep the RPM under 5,500. Do that and it will be great fun and last forever.

Post some pics, everyone would love to see the project as it progresses.