Ok, let me lay out some hard truths here:
1) probably 90% of cheesesteaks use wiz or American.
2) usually, the only vegetable option on a cheesesteak outside of things like cherry peppers or pickles are fried onions
3) roast pork as found at John's or DiNics is superior to cheesesteaks in every way. I like mine with provolone, rabe, long hots and extra jus
4) no, roast beef won't adequately substitute for thin chopped ribeye.
5) bread will make or break your sandwich. It should be soft and pliable enough to wrap the meat like a warm blanket, but crusty enough to not fall apart. Has to have good chew. Same rile applies to roast pork or quality hoagies.
6) also, WRAP the sandwich in something. Parchment, foil, wax paper. That way the sandwich doesn't fall apart
Any questions, send PM.