will 3 1/2" offsets fit? Alum slots on 74 Duster?

I was just wanting to get something like 60 series, dont need much bigger. I just want to fill the wheel well up some. I have 14" ralleyes now with 205/70 front and 235/60 on back. Was told that this was the widest that I could get in the back and still be safe. I like the looks of the slots with the yellow body paint I have now.

I wonder if I could paint my ralleyes black, but Im thinking that may be a little much. My duster is yellow with black side stripes and black twin racing stripes on hood and trunk.

So these slots I first mentioned would be too wide? For the tires that will fit and look good on? Hate to pass these up but dont want to waste money with something I wont like.