summit cam selection
For what it is worth, I ran the .420/.442 cam in my 318 with unported 302 heads, hedman headers and Stock Intake Q-Jet Carb in a heavy 5th Ave with a 2.2 geared 4dr. It even had a slight lope(you could tell there was a cam in the ole 318.). The low end suffered some, but the mid range was much improved.
It would be easy to say, go with the bigger one and it is very tempting. However, since it is going to be a 100% and if it is going to be driven alot I would suggest the smaller of the two. Even though I am comparing my Pineapple to your orange when it comes to the vehicle.