318 with 360 heads and compcam build help

That cam has a LOT of duration at .050! If you must use that cam then you're going to need 3.91 gears, or higher (numerical), and a higher stall converter. The car will not idle in gear with that cam and a stock torque converter. Regarding the head choice, 318 heads will run out of steam right about the time that cam is going to start pulling. The 915 heads with 1.88/1.60 valves would be the better choice. Depending on the current cc on the 915 heads, you will need to mill them to get some sort of compression capable of supporting that cam. How much to mill the heads depends on what piston and its compression height. If you try to slap it all together without doing the above, you'll have a dog of a combination that you'll be very disappointed with. My suggestion, if your low on funds, is to sell what you currently have and buy a complete good running stock 360, slap a cheap used aluminum intake, a 4 barrel and add headers. You can use your current drivetrain and the car will be plenty peppy and you can upgrade over time. In my area, running 360LA motors go between $400-800. You'll spend way more than that trying to get the 318 built with the parts you have, and the 360 with above bolt-ons, will smoke your desired 318 combo. Just my .02 worth.