Howdy fx2nut:
Your '62 170 came from the factory with a fairly weak, prone to cracking, exhaust manifold with a 1.75" outlet with a flat gasket to seal to the head pipe. The head pipe and exhaust system of that year was 1 7/8" on a 170.
The '68 manifold has several advantages; it is heavier cast with bracing gussets making it less prone to cracking and warping. It also has a donut type seal to mate it to the head pipe, which is a much better system. And it has a 2" outlet.
The stock OEM exhaust manifold typically came with no exhaust manifold gasket to help seal it to the head. And, to answer your question, I doubt that there is a kit available specifically for your combination. IIWIYS, I'd find the friendliest exhaust shop in your area and specify that you want a complete system in 2" diameter pipe with a turbo type muffler.
I don't know what other mods you may already have, but you should notice slightly better throttle response and a slight increase in mileage (IF you can keep your foot light). It will also be a lot safer for your health with fewer chances of exhaust fumes.
Keep us posted on your project.
Adios, David