| Kaisoku |
A ghast is an advanced ghoul. See the PRD entry here. Specifically, at the bottom.
Note that the 3.5e entry for a Ghast is a CR 3 encounter, but the advanced monster template added to the Ghoul in Pathfinder only gives it a CR 2.
You could maybe increase the number of creatures, or just add another hit die to the Ghast to make him fit the conversion for the 3.5e encounter.
| Wolf Munroe |
Bestiary 1, page 146. Ghasts are advanced ghouls.
Ghast
Ghasts are ghouls with the advanced monster template. A ghast's paralysis even affects elves. Ghasts roam in packs of their own kind or lead groups of common ghouls. The stink of death and corruption surrounding these creatures is overwhelming, granting them the stench extraordinary ability (10-foot radius, Fort DC 15 negates, sickened for 1d6+4 minutes).
| Volaran |
| Drejk |
Second if I can not find one what should the CR monster be if I have 6 1st level guys.
Gamemastering section suggest treating parties of 6 or more characters as if their Averge Party Level was one higher which sets CR of average challenging encounter at 2 instead of 1 and of epic encounter at CR 5 instead of 4 (still care must be used as single CR 5 monster can easily mean TPK for 6 1st level characters - multiple lower CR monsters should be rather used, on higher levels that +1 APL adjustment works much smoother).