Replacing spark plug wires

So I'm new to the engine maintenance. My cool wire was recently not attached properly and has burnt through the connector. So I'm trying to replace the whole set. Recently purchased new msd 2 coil and have no idea what size wires I should get. Msd says to use theirs and that is 8.5 mm for 318 la duster. Does the size matter in wire replacement? I'm stuck here and need help

Yes, size matters....(LOL) but the 8.5mm should be just fine.

Jeff