Hey Red,
Tire clearance will be a big problem, especially in the rear. My old '72 128 sedan had 165/70R13 tires on X1/9 steel wheels (13x5") and they rubbed in the back if I carried passengers. Look for a rear spring from a wagon to stiffen the rear and watch tires size and wheel offset (with spacers if using them) carefully. There is not much room between the rear struts and the inside of the wheel well.
I am going through this myself because I want to upgrade to bigger brakes. I will be running Alfa Romeo Alfetta 14x6" Campagnolo wheels (4 on 98, 58mm center bore, 36 mm offset) with 20 mm H&R spacers. 185/55R14 Yokohama A052 are 22" diameter (945 revs per mile).
I know a guy here on the forum who was running 15X6" Fiat 500 steelies using 195/45R15 tires. He took them off and switched to old school 13" wheels. Honestly, I love my 13s. The only reason I'm switching to 14s is to fit bigger brakes. The Maserati BiTurbo wheel is the easiest and most cost effective solution, no spacers required and bolt right up with longer lug bolts. I just love these old Campagnolo wheels because I had a set on my old Alfetta racecar.
BMW OE E30 alloy wheels will work with your adapters and give you basically my setup. The 14x6.5" 325is wheels may be too wide, I am not sure. Mk1 VW GTi wheels will also work. There are cheaper 185/55R14 tires than the Yokohamas if you don't need or want that much grip and that short a tread life, but the choices are very limited.
Have fun with your engine swap. The injection will fit. 75 HP in a 1700 lb car (your car if you remove the bumpers) feels pretty fast. These engines are smooth and love to rev.
Chris