I believe Pat's and Geno's are both open 24 hours- although I could be wrong. I've never heard of either one of them "running out," and as for that line around the building? That's pretty common place no matter what time of the day you visit. Jim's can get like that too depending on what time of day you go. It's par for the course of getting a cheese steak
I'm not sure about the other roast beef creation of a sandwich- but I know there are tons of Italian style delis and I'm sure any of them could whip you up any amazing sandwich of your choosing.
If you have time go visit the Italian Market on 9th Street- delis, bakeries, butchers, spice shops...you name it.