MSD wires..which to buy?

[72CampSpecial]

#6 Spark plug wire at the boot keeps getting burned/melted (3x's).. even after i dropped a HEI in with 8mm wires...so im looking at getting new wires that might last more than a month..

Locally i can pick up the MSD 31229's for $81.00...but have read that the MSD 5566's are good too and cheaper.. (not sure if those are local or ill have to order).

I could also order the 5566's and then order the kevlar sleeves that ive seen some guys use.. ??


Truck: '72 C20 Camper Custom, w/'75 HEI installed that i pulled from a GMC, Stock 350 w/Stock exhaust manifold.. think its call a ramshorn (?)