96GT226410

What else has to be changed to swap from a 96 non-PI motor to a 99-04 PI motor? The last Mustang I had I just did the head swap and I blew out my lower end due to the raise in compression, so this time I want to do it right. I figure this motor would be a good starting point for me..... I have a set of 3:73's that are to replace the stock 3:27's. Is it really necessary to set pinion backlash with shims when swapping gears? Or would it be okay if I just used all of the old shims and the old crush collar?..... What about wheel spacers? Are those just wastes of money? I have 275/40/17 in the rear and am going to lower my car. I was going to put them in if the tires wouldn't bee too close to the exhaust. Would wheel spacers help the handling? Anything you guys could help me with. Thanks...