not likely to find original pipes unless you stumble on some NOS someplace, but if you check around older muffler/exhaust shops someone may have the spec card for bending them up - the crossover pipe will be the hard part, but a good exhaust shop should be able to make one up .... other wise any shop could make up the needed pipes for duals, which wasn't the original way, but works and sounds nice w/ a 283
Bill