Help me decide on the best course of action

[Tynee]

General background: The '70 in my signature is my daily driver. When I bought it, I looked at the ground under the truck and there were no oil stains, and nothing was leaking. After driving it for a couple of days, it developed a pretty decent sized oil leak. I've been keeping oil in it and waiting until the right time to repair said leak. It's the expensive method of maintenance.

Specific background: Tuesday morning when I got out of the truck at work, I noticed a little puff of white smoke, but didn't think much of it, sense it was a fairly cool morning. Wednesday, I jumped in and headed to the gym, as I was pulling into my parking space, I realized I never did get any heat all the way there, so I checked the gauge, and it was PEGGED. Its an inexpensive aftermarket gauge, and its not backlit, so I hadn't noticed in the dark that the temp was high. Well, after I finished at the gym, I went to investigate a bit more, now that the truck has cooled and I have some daylight, and found that there was no coolant in the radiator. So, I jumped in and limped down tot the closest gas station, filled up the gas and the radiator, then headed for work. I watched the c temp gauge all the way to work, and everything looked good - the truck ran like it always does. When I got to work was when I noticed the steady stream of white smoke from the tailpipe, I jumped out and smelled it, and it smelled a little sweet, so I checked the oil. The color was good, but the level was high. I took the filler cap off, and it was milky under the cap. SOOOO - Long story short, I'm assuming I blew a head gasket.

My plan: I believe that my oil leak is coming from the rear main seal, call it a gut instinct. I intend to buy a gasket set that includes head gaskets, manifold gaskets (intake and exhaust), main seals, oil pan gasket, and valve cover gaskets.

Here's where you come in: Do I want to pull the engine and do all this work on the stand, or would it be a whole lot easier to leave it in the truck, and do the main seals laying under the truck, and do the top side work under the hood? I'm a pretty decent wrench, and can pull parts and replace them with the best of 'em. My buddy and I swapped motors in a small FWD Mazda in basicly 2 solid afternoons. I spent the better part of a week changing the intake manifold gasket (twice - don't ask) on my Wife's old Grand Cherokee.

I'm looking for some input, guys. Also, is there another possible source of a fairly major oil leak that I won't be addressing if I do all of the work I've mentioned above?