Accel has come out with new spark plug wires that combine good RFI suppression with very low resistance. A quick Google search found a comparison of racing wires at SRT Forums.com and these Accel wires at 25 ohm/ft came in between the top two in this comparison: Granatelli wires, at an incredible 2 ohms/ft, and MSD at 33 ohms.
They use Ferro-spiral core that is machine wound to allow maximum spark energy to the plugs. The red wire jacket features a double silicone construction that is rated at over 600° F. This extra layer of silicone is designed to better resist extreme heat variances, petrochemicals and excessive moisture. The special Race Wire terminal uses a combination of stainless steel and brass for unsurpassed electrical conductivity and excellent corrosion resistance. Using Kevlar strands on the inner core provides greater pull strength and robust terminal retention. BTW, Granatelli uses a stainless steel core, wrapped in silver plated copper wiring.
Summit racing has universal kits for $100 and SBF sets for $160. I really haven't shopped them, so I don't know if this is a good price for these wires in particular or as wires go in general. But they sound like a really good spark plug wire to use in a GT40.