10" rubber under stock 71 Duster???

I've been reading threads about tire size and fittments under particular A bodies hoping to get the answer to this question but am still not sure of the answer, as well as about spring offset kits etc. I know that 29 x 9 x 15 fits but is that the max with out spring relocation. I was hoping to find street legal slicks in those dimensions but no luck. As soon as you get that tall they are 10" or 10.5" wide. With my 4:30 gear a 235 60 15 at only 26" dia is too small. Will a 10" tire fit? I bought 15 x 8 weld prostars with 5 1/2 backspace for the rear, 5" wide for the front.
When I bolt the bare wheel on it seems a 10" would rub on the spring. I've seen somewhere in my search about spring relocates that only move in about 3/4" with offset shackles at the back the but I can't see how the front would move since the spring is against the frame. Any info appreciated. Kev

here's a picture of my duster with 275/ 60 / 15 also had 28 x 10 x 15 slicks on it. all in stock location of springs. it's all in the rims backing space.

pic