Does anyone know what the gains are by using a 160 degree stat?

 

Nowhere near what people are going to tell you. I have one and am debating trying a 180 again based on the fact my car often goes faster hotlapping than it does after a cooldown . I have been doing some serious burnouts too so it is not just a tire heat issue and better stick on the second run.

That said there are those who will say the heat is bad and such with a 160 stat and that is just not the case either. For several years the Caprice was my only car and I drove it through several Wisconsin winters with the 160 stat and TB bypass just fine.

 

Changing to the 160* t'stat will provide some benefit if you also adjust the tune to turn the fans on sooner, and add a couple degrees of ignition advance..... probably more of an advantage with aluminum heads (F-Body) than with iron heads (B-Body). I've seen dyno tests that showed improvements in the range of 10HP.