This is about the best answer so far. You need to run more initial, for a cam this big in a motor this small with relatively low compression, you will need about 18 deg. Alot of us talk about more initial on here, but no-one ever explains how to get it, we tend to assume you know, and that may not be fair. You have to disassemble the distributor, and add material to the outer ends of the advance slots. This is a trail & error deal. You can start by adding about 3/16-1/8" of material to the end of the slot. The idea is to add more than you need, then test it, grind a bit out, test again, till you get it where you want it. I recommend gas welding the end of the slot, as the weld will be a little softer & easier to work than mig. You need to have a timing tape or degreed balancer on the motor. Plug the distributor back in the motor,leave the vaccum advance off for now, set the total timing at 2500-3000 rpm to around 35 degrees and let the engine drop back to idle, check the initial timing. With the slots welded up, it will probably be over 20 degrees. Disassemble the distributor, grind a little material out of the slots you just welded up, put it back together & repeat the process until you can get 34-35 degrees total with around 18 degrees initial. At this point, go back and re-set the idle speed/mixture screws.
Next, you are probably gonna have to go into the carb. If you have the initial where it should be, but the engine is still unresponsive to the idle mixture screws(pretty likely with this cam in a 318) the throttle plates are still too far up into the transfer slots, and the engine is not idling on the idle circuit. At this point, you need to go in and drill a small hole in each primary throttle plate, just ahead of the the throttle shafts. Start around .080 (on this combo, you will probably be good to go at .080) and work your way up, until the engine is able to idle with the throttle plates almost closed.
By now, this thing should be idling pretty nicely. The 108 lobe separation is an ADVANTAGE with the 318. It will help increase cylinder pressure relative to the wider lobe center cam, and it will pump up the mid-range torque. You just have to know your tuning basics. Big cams are not for the "bubble-pak" crowd, you have to have the skills to tune them properly.
This stuff is ALL trail & error, DONT just go in and drill the holes in the carb, do it in the order suggested, work slowly and methodically, step by step, and not only will your car run better, but you will really be learning how to tune properly, which will put you way ahead of the vast majority of guys out there that are jsut bolting parts together & hoping for the best.