I did the math last night and compiled a PFPX aircraft template from the limited amount of performance charts I could find for the DC-8.  That being said, its 5:30am here and was able to run it through pfpx; however, have not had the time to actually test fly with the numbers it generates.  Therefore, use at your on risk. If anyone has any feedback please feel free to share.    Furthermore, If anyone has come across some "holding" and "descent" performance charts please let me know and