Shimano first generation chain rings wanted

[sdaines]

I have a 1977 Coppi road bike with first generation Shimano 600 3 bolt crankset. I'm looking for 52 - 53 tooth large chain ring, and 37 - 39 tooth small chain ring. Looking to do the Houston to Austin MS150 end April and the current 51/44 chainrings make the hills really tough! Many thanks