If you become a vampire of a different clan than Orlukh, then complete the "Iron and Blood" quest while wearing Namira's Shroud, Budak will still offer you his blood as a reward. However, you won't turn into a vampire (at least on OpenMW), and your Porphyric Hemophilia will remain forever. Since Namira's Shroud script is currently broken (as far as I know), I don't know how it could be fixed. Maybe just add one more dialogue entry, filtered for PCVampire == 1.

UPD: If you do the same thing while being an Orlukh vampire, Budak will recognize you, but won't open the gate and won't recognize your progress in the quest.