That's really hard to compare since I used some parts from my Sema truck on my daily. My daily was down for a few days while I was prepping and painting everything ON the truck. I would say a couple of weekends worth of time, and then enterchanging parts from my 94 to the 2000. Valve covers, fan shroud, air intake etc...
It does get dirty...
http://www.jancecustoms.com/2000_dodge_ram_daily_driver_engine.html
As far as the Sema engine goes, I won't even guess at how many hours I have in smoothing out the engine, polishing the intake and transmission, smoothing out the spindles, door jambs and everything else. Trial and error and a lot of patience.