The Borg Warner 171702 turbo is the right turbo for the 12.7 (no waste gate). The optimum turbo is the Borg Warner Air Werks S400SX4-75. These are similar turbos that PP sells, but you can get them cheaper elsewhere. They are also used by some racing heads in various smaller engines. I couldn't seem to find any indication of the turbo you mentioned as right for the 12.7. I am assuming here that your DDEC IV is a 12.7 and not a 14L. The turbo you mentioned does have a T6 footprint, which is the correct size for 12.7 application, so it might be just fine.
Prices are reasonable on the web. I found the BW AW S400SX4-75 on Ebay from BuyAutoParts listed for $824 with free shipping. That is a good deal for this top line 12.7 turbo. Will be purchasing one of these for my 12.7 in a glider truck I just ordered.