63ChevyII, I would wait. When I did my swap, I did it with the stock exhaust manifold and cut the pipe and put a "shade tree" patch pipe with some clamps to extend the legnth till I was able to switch to headers. When I made the switch to headers, I just used some flex pipe to some glasspacks temporarily till I got to the exhaust shop. That might not be something you would want to do if you are going to show it, unless of course you don't mind. I wouldn't mind. People have to realize it's work in progress..
