Issues with a rebuilt 360

Stop spending money and fix what you have. If the main body is on backwards, who knows what else is wrong in there.

If the idle is high, it’s getting air from somewhere.

You can take the carb apart, look at what you have and post it here. We can see if anything else is wrong and help you get it back together.
I’m definitely going to flip the main body but the efi system was more of what I plan on doing in the future then now I know it’s getting air from somewhere but the only place I could see it maybe could be getting air from is the headers