Mopar small block fan routing diagram

That W/P pulley does not look right to me, and the alternator looks to be too far back.
I have not had an A/C car for many years, but non-A/C cars always had the P/S run a separate belt by itself and it goes on last;just like in mirages post.
Check out Mirages pic, that is exactly how everything is supposed to look like. Notice also the support bracket BEHIND the P/S bracket.Notice the shapes of all the pulleys. And especially notice the alternator mounting bushing/spacers. With non-stock heads you usually have to offset the alternator to properly line up with BOTH the crank pulley and the W/P pulley. This often requires shimming and or bending the brackets and the adjuster strap, or digging through the parts bin for a better fitting part.Make sure the short bushings are in the alternator mounting ears.
If you had all stock, correct vintage parts, then an off-the-shelf belt would work. But I don't see any stock parts on there except maybe the P/S pulley. The dual alt-pulley did not work on my car, which looks exactly like in mirages post.I had to swap it out for a single grooved one. I slowed my pump and alt down as much as I could, with raiding the parts shed, cuz I just knew I'd be missing a shift now and then. And flipping a belt off is all too easy with the stock ratios