Like the 5.0, you have to remove the front crossmember before you can remove the oil pan. I'm not sure what all is involved in that.
Are you sure the oil pump is bad? Did you start it up and listen? You may want to do that, listen for any unusual knocking noises. Check the gauge. Many times people think the oil pump or some other oil flow problem has occured, when actually it was just a faulty oil pressure sender switch. Those senders have a habit of going bad.... very often.I replaced mine twice, and after 2 years, it's going out again. I would check to make sure. The seller might think the oil pump is going out if its only a faulty sender. Find out the exact specifics. And just in case it IS just a sender, don't tell them what you think you may know, otherwise they're liable to jack the price up.... hint hint.