Is 9.7:1 compression on iron heads too much for 91 octane

Slantsix64 said
I dunno if this is the correct way of lowering your CR by using thick head gasket .54 felpro head gasket? or install a more aggressive cam?

Sure nuff. Other than changing heads or pistons this is the simplest way. Many use thin gaskets to raise compression. Thicker ones can lower it.