'71 Demon Pro Street/Touring

I forgot to mention the reason I call this a pro-street/touring build is because for now all I can afford is the Welds/MTs combo I have for the car so far. I will keep these later for track days. My plan is for 20x12s on rear and 18x9s up front, not sure on rims yet but rubber will be 335-345 wide in rear and fronts 265.
Of course if the mood strikes to have a drag look on the street I can always swap anytime.
I also did not narrow the rear end, for yet another option of running large bolt pattern Rallyes if I want to go for a very stock look.
Heres a couple pics of the rubber rim combo I have so far, rears are 29x12.5 and front are 26x4.5 Sportsman Pros. Welds are S71 10.25x15 rears and 4x15 fronts:



I'm also contemplating a plan for street/touring wheel/tire changover capability. I've been unable to find 17" or over rims with a low backspace that I would like, say 3.5 to 4 inches to allow swapping to a similar 15" rim. Of course the diff needs narrowing and a mini-tub for this to fit tucked under (no jacked rear and tires sticking out for me!).

Seems one has to run a high offset rim like 6" or so to make this work unless I'm just not looking hard enough. Sad as I like the deep look of low backspace on the rear.

What's the offset on your Weld rears?