I have a 87 gutless with a 307 ycode, I have a miss on cylinder 6 and I think on 5, was thinking of going to a hei vacuum advance distrubtor rather then the stock CCC distrubtor, I know I need to change the carb, my question is is this worth a try or not

 

This might just be a general tune up issue. What I mean by that is, a cap and rotor, spark plugs and wires could probably fix this. Check for vacuum leaks real closely also.

You could still go with your plan and these parts would still work.

Welcome to the site Eze.