Decided to try installing the engine and trans from below. Headers are installed, starter is in place, coils on the valve covers, etc. Basically a fully dressed engine.

I have the car on a set of casters so I just lifted the front end up in the air a bit and rolled the engine and trans underneath. Then lifted the engine and trans in from below and bolted it in. Everything cleared except for a couple of plug wires. The coils clear the frame rails by 1/2 inch on each side so you have to keep things lined up when lifting the engine in place. Headers clear by a bunch on each side.

Looks to me like this is the way to do it, especially with these huge headers. Once the engine is in place the headers are a pain to install.