Are you going to assemble the whole dash before installation? I found that it was pretty easy to install all the gauges/wiring/duct etc on the bench and then install it all in one swell foop. The only gotchas I'd watch for is to stuff a rag into the defrost ducts so you don't have to R&R the dash (don't ask). I also had to remove my dash light dimmer switch after installation. It worked when it was originally removed ~15yr ago so I assumed it still did. The copper was all corroded and needed to be cleaned so I didn't have instrument cluster lights at all.
Other than that, it was much easier to assemble since I could get to everything easily on the bench without having to lay contorted upside down in the car.
$.02