Wheel spacers

I've got a 73 duster with a big bolt 7 1/4", 2.76 open gear. The way I drive, I'll probably never hurt the wimpy rear and I'm not sure that going to a 2.94 or 3.23 gear would really be worth the effort to install a different rear axle. I definitely wouldn't put the money into the 7 1/4" to re-gear. Anyway, I've always hated the way the rear tires are tucked in on the car. I've got 14 x 6 rallyes with 4" backspace and 225/70R14 tires with 1/2" clearance to the springs and
2 5/8" clearance to the quarters. I am a machinist by trade and could make my own wheel spacers if that is not a dumb idea. I would probably want about 1 3/4" but I'm just not sure about the safety aspect of that. I also don't know if it would be better to make bolt-on spacers or straight spacers with longer wheel studs. I would make them hub-centric either way. On my bucket list, the next time I need tires, I would like to go with 15" Torque Thrust wheels in which case I could go with a wider rim and not need as much of a spacer.