Dayum, that's shiny! Be careful opening the hood on a sunny day, the reflections from that fan spinning might down small aircraft!
I presume you are not putting a somg pump pack on, or never had one, so...
I'd grab an alternator belt for a '70 Caddy, run it crank, water pump, alternator.
For the power steering, I think you'll be on your own, all the stock belts for the power steering ran around the AC compressor so would be way too long. You might try the alternator belt on that side, that might work. , but you'll probably need one a bit shorter, and run it crank, water pump, power steering. There are two grooves for that routing, but I think that was mainly because of the AC, so you can probably just run one belt to the power steering.
The power steering pump body is spaced away from the block on the 2 adjuster mounts. If you don't space the pump the belt will not line up and wear develop a fugazy wear pattern. A couple a three washers work here if you don't have the original specialty hardware.
Thanks for the compliments, diagrams and suggestions. Someone asked if the manifolds were chrome...yeas they are. I realize they may turn a little but not as bad as headers because they are a thicker metal. besides I had them ceramic coated first and it looked HORRIBLE with all that chrome.
It is a 472 not a 500 and I have between 1500 and 2000 in plating on the motor. not sure how much I have total because some things were upgraded. all chrome holley: $625.00 building a chromed out and candy 472: PRICELESS
For the P/S belt, I could check my manual for the correct size.
Remember you could buy the cars without A/C (heat only) it uses the short belt. I think autozone.com will give you the correct P/N if you look up a 68-72 Deville w/o A/C. Some stores and some sites don't list it for certain years though. But, the 68-72 cars all had the double belt for P/S and A/C. Find the no-A/C P/S betlt for one of those years.