Jeff,
The FelPro gasket has a .039” compressed thickness.
There are also thinner head gaskets sold by Rocket Racing in Wisconsin.
http://shop.rocketracingshop.com/Head-Gaskets_c96.htm
I know you are trying to make this project a low budget, however, due to the small bore of the Oldsmobile 307, I would recommend going with a custom Cometic head gasket with a smaller bore and proper thickness.