As HRL said, if you're not worried about car-show snobs, convert to HEI. One consideration is the rotation of the distributor rotor. Unsure if caddy engines turn clockwise like a chevy, or counter-clockwise like a Pontiac. Figure out which way it turns and get the corresponding distributor. Not sure if you'd have to use a distributor out of a caddy, or if another GM unit would work. Compare shaft, gear and oil pump drive tang dimensions on your distributor to the candidate HEI unit. You'll then have to re-curve the HEI to get the optimum spark advance for your engine. Still not a big problem.
I've used 14 gauge wire to power HEI ign systems up to 5,000 RPM. Don't wanna turn a stock-rod caddy engine much past that anyway. HEIs only require one wire from a switched 12 volt source to run. Most important thing is to eliminate ballast resistors or resistance wire in stock distributor power circuit(s). Other slight wiring mods may be needed to get power from key to HEI unit during cranking and run positions of key. Or you could convert a stock points-style distributor with a Petronix kit for a stock appearance. Either way, we can talk you thru it.
good luck
HRB (aka CH)
