I went through the same issues you did. Purchased the car which had 17x8's all the way around with incorrect backspacing.
Took my time with the measurements and ordered set from team III in San Leandro.
I have a 2007 B&B with the shortened 9" rear and front tubular suspension. I went with 15 x7 in the front with 4 1/2" back side setting and 3 1/2" on the front side.
For the rears, 15x10 with 5 1/4" back side and 5 3/4" front side. I have 235/60/15 Firestone's in the front and they rub at full crank on the inside of the fender wheels. Rear's are perfect, running 295/50/15.
Here are some pics
