318 timing mark

15 initial on ported would be a good start. I had 18 on a stock '83 318. You could set the initial with the vac gauge method then shorten the slots to get 35 total (initial+slots) then toss the heavy spring with the elongated loop on one end & sub in a MP or Mr gasket light spring in place of it (you want a spring combo that keeps you a moderate bit below the pinging point at WOT up thru the gears on your hottest/driest (most likely to ping) day and any spring combo once you toss the elongated advances in a linear rate then plug in/adj the vac can. Short (easiest) version: set initial to 18 (you have a cam)/toss the elongated spring/sub in a lite one there & call it good. bottom line if NO pinging & no balky starter on cranking & no overheating from retarded timing (not a worry there but throwing it in) then you are fine. there is silent ping so you wanna stay a reasonably amt below the amt that makes it ping but you want to be pretty close to that line also for max efficiency