True on the coil but for some reason the GM small on trucks, what we mostly saw, tended to really corrode on the caps. We always used the brass terminal Blue Streak caps in the shop I worked at years ago. Everything has their negatives.Since HEI is electronic, you really should use carbon core suppression wires to avoid EMI and RFI in the electronics, especially if you are running CCC or EFI. Spiral core stuff generally costs more yet does a much poorer job of suppressing EMI with no ignition improvement. The ignition enegry travels through the magnetic field around the wire.
Coil in cap ignition coils are a compromised design. In order to fit in the tight space inside the cap, they have to use thin windings and insulation which makes them weak. Not to mention being in cap results in them retaining more heat which promotes coil overheating which aggavates the thin windings and insulation. There is a reason for remote coil conversions.