what plug wires would you use

well I managed to get this junk yard dog running and it sounds good but it has a little miss in it. I put a mix matched set of wires on it when I freshened it up and I think it may be in the wires. It is a 360 and I believe it came out of a 78 or 79 whatever. I think the wires I have on it now is 7MM and I don't think that is right. I was thinking of putting either 8 or 8.5 MM on it. It is a stock driver, nothing fancy. what do I need to put on this thing. Thanks,Bill