Fiatallis 11b

i have an issue I need help with... Long story short, I ran dirty fuel through the system and that destroyed my injector pump... Took the pump off and tried to get it rebuilt... Diesel pump shop says it's going to cost way to much to find parts for it and I should try to find a good used one to use instead. I have googled to no end and still have no luck. Where should I look?

Old pump model is: stanadyne dco 631-3000



Thank you in advance!

Fiatallis 11b