What cam? I got a low compression 73 318 and I'm not so deep I can't change a cam. I just dont want to end up with a low end dog..
Try something in the 260° - 275° duration with around .450 - .480 lift with a lobe center line between 110° - 114°....
The higher the lobe center line, the less overlap for that particular duration and the more cylinder pressure you can build to compensate for the "low" compression...
Then throw in a set of Rhoades variable duration lifters that bleed down at idle and give full lift and duration by 3500 RPM when you need it... It will add more low end and mid range torque and HP, increased idle vacuum, smoother idle, and will increase MPG...
Rhoades lifter main page:
Rhoads Lifters
Read the articles on how they work, especially the second one:
Articles
Another thing that I could suggest is to run a set of 66 - 67 273/318 heads, the 920 heads with the closed chambers... The smaller combustion chamber along with a .040" head gasket can increase your compression between .75 - 1.0 point of compression... I am doing this with a stock 72 318 block that I am putting in my 66 Valiant wagon...
Only the 64 - 65 273 heads had the unique intake bolt size and angle, the 66 and later heads are all the standard intake bolt size and angle so you have a variety if intakes that you can choose from...
Many people can't give an old 273 away, so you can find them cheap... Offer the guy $100 for the whole engine and take the heads and get them done...
I had my head guy go through my 67 920 heads and clean up the ports, then open up the bowls, gasket match the ports to the gasket, install 1.88" intake 360 valves and the 1.60" 360 exhaust valves and installed hardened seats on the exhaust valve so unleaded fuel won't damage the seats....