Keep in mind that changing wheel or tire size will change the amount of scrub radius. The standard 28-29 model A axle is engineered for a 21" wheel, my tires are only 22" in diameter. Using the same backspace as stock with 15" wheels and small tires, the scrub radius would be way out of whack compared to stock. Set up with tires you intend to run.
YMMV
Ron