Hi Bob! Good choice of mfr, of course
I'll add my comments to all that have posted already ...
Unless you are skilled and very particular about how things are done, I would have the body and frame mated at ERA. This is a complicated body, with lots of close fitting bonds and a jillion rivets. And ERA's price to do this is a bargain. They'll do it right. Also think about having them do a complete rolling chassis .. again, a bargain.
Avoid heartache .. have ERA do your pipes soup to nuts. They can have whatever muffler you choose fabricated into their collectors. You must buy the ERA primaries, they are specific. And they have jigs to do the mounting brackets and tabs for you, so you won't have to weld. Mine fit perfectly, not easily, but as designed. Bring lots of vaseline
I didn't buy all the gee gaws discussed earlier, but you should get everything you think you might want .. don't plan on doing it later. I didn't order a heater .. it's really generic and the next owner (if there ever is one) can certainly add that. I don't need one in TX. Didn't order the top either, but in your area, a good choice. Again, have ERA do the fitment.
Having the rolling chassis painted while at ERA is really worthwhile, they will send it out after bonding to the frame, but before installing all the pretty aluminum panels. Cost is the same for a quality paint job there as anywhere .. unless you are the painter! You deal with the painter directly. They have painters they regularly sub to .. I used Tony .. a bargain, but perhaps longer cycle time by a few weeks.
Good luck!
Sam