Best 416 small block, 727 auto, TTI installation order?

Ok, I'm at the point where I can now drop in the new engine, new 727 transmission, and install the headers. This is a power steering car and was originally a 318, 904 car. I have all new 340 mounts. Hood is off. The question that keeps going through my head is in what order. I did a search in the archive and found nothing.

Since I have the three main pieces all out, what would you recommend for the order of installation?

Would it be better to get the engine and transmission in and then raise them for the header install, OR...

Lay the headers in, drop the engine in, then install the tranny, OR....

Install engine and tranny assembled while headers are sitting in place????

I'm obviously looking for the easiest install. No reason to create extra work if not needed.