Dash removal----How difficult is it?

[327chevy]

OK it's getting pretty cold out and nobody wants to ride in my truck,at least in the passenger seat,so it looks like I'm going to have to go really in depth into this draft problem to find the problem.What I think I'll do is remove the dash all together so I can get a really good look at the inside of the fire wall and all the heater hoses and hopefully trace down this annoyance.

How big a job is it to take out the dash?I've got a Haynes manual to help me so I'm not completely blind here but any advise would be great.