Very brave. Having lived in the Philly area for almost a decade an having eaten my body weight in cheesesteaks, I'd say it would be pretty difficult to make a cheesesteak at home which would convincingly fool at native, but you can make a decent version.
Cheese Whiz: impossible to get here, but you can make an adequate substitute by melting medium cheddar and stirring in a small amount (very very small amount) of sodium citrate dissolved in a bit of water. You will get a cheese dip consistency which will not curdle or get stringy.
Meat: Thinly sliced ribeye. Buy in a slab, freeze until slightly frozen and slice very thinly. If you have one, cook on an oiled griddle and keep the meat moving. Don't overcook the beef.
Bread: closest thing to a set roll is a white bap.
Allow the onions, beef, Whiz to rest in the bap for a couple minutes prior to eating so that it absorbs some of the juices and gets to the perfect texture.
Scroll down this link to the photo of the Dallesandr's cheesesteak for the ideal composition (I make a special hour drive here every time I'm home - so worth it!).
Good luck, and let me know how it goes.