Mate, I can measure mine up tonight, but both my Sprint and my 33 are with the same rear axle.
Ideally I should measure the one out of my Sud, which has the same suspension and brake setup as your Sprint (inboard front, discs rear), but its currently at the paint shop, so cant measure it today.
Worst case scenario, you make your panhard rod adjustable, and benefit from centering the rear axle as well.
Biggest headache for me when doing thinking of doing this conversion (couldnt be bothered) was changing all the brake lines, needed the bigger servo unit, had to change the pedal box as well in order to make them fit, changing the suspension again, needing to find stiff springs for the 33 suspension which is a real nightmare, etc etc etc...
My advice is, leave it as it is, and refurb your front calipers.
Just as efficient when they work properly, and you can keep the rear discs