I have a 1980 mont 355 convert to 4 speed. I recently put on a new professional products hurricane edelbrok 1407 750 an msd street fire hei dis in. I have a dead miss under a load on num 6 plug I can almost make go away at idle. I pulled the #6 wire an put in a test plug to c if it was getting spark u could weld with the out put . I've re placed wires an plugs. The ignition is completely new. The plugs look. Like they never been used when I went back through an checked them. So I'm guessing its running lean but it smells like its running rich. I'm lost could really use the help