i need to know:
17x7 +34 ... all 4 will be the same size/width/everything.
running that on a xB.
how will that fit? will it be low enuff offset?
keeping in mind the width of the rim is still just 7(not 8 or 7.5)

It will look good but you still could go lower. Im building hubcentric spacers in various thicknesses for myself to play around with so if you need any, let me know :)

IMO, i would slap a 5mm spacer up front and 10mm in the rear in your situation.