Well, I will answer your original question. I personally like the 308 heads off of 89-91 360's. You will gain a lot of flow, however, you will loose some compression. Have them cut about .040 and that will help. If you are willing to put different pistons in your 318, like KB pistons, then cutting the heads would not be necessary. I would suggest a 670 street avenger holley carb on a weiand action plus intake. A cam that is roughly the size of a stock 340 would work well, or maybe a little bigger (not much). So, the carb, intake, heads, cam and headers should get you a little more than 300 gross horsepower. If you bore it .030 over and use KB piston, you would be even closer to the 350 mark. But, this combo would need at least a 2400 stall converter, and at least 3.23 gears. More stall and gears would even make it quicker. Finally, yes, the 360 magnum would be a great choice....