[P3D]

Hinnom won't be a research lead, as the IIRC 125gp is not that good a price for 4/5RP even without a lab.

About Gath, the best option for research IMO is the S1N1 Sybil for 80gp, not sacred so won't need 80gp temples, and have 5% Fortune telling to offset Misfortune scales somewhat. The 50gp sages are a bargain, but S1N1 just offers more combat potential late game, spamming S2/S3/N2 spells by the dozen (Rev. communion, LotNS), and if you were not recruiting Sybils you won't have the numbers.