Heater Bypass Nipple Seized

I recently bought a car with a 76 318 engine.
I pulled the front off the engine to do the timing chain and discovered why the bypass hose always leaked.

It looks like someone installed a gas fitting with threads the entire length. The hose never gets a seal on the threads. This thing is black iron and is a nasty rust mess. You can see from the stains in the picture it leaks a lot.

Now the problem….
I soaked the thing in home brew penetrating oil (acetone and transmission fluid) most of the day while I worked on other things. I used an internal pipe wrench and a two foot breaker bar to try and free it. The thing is not budging. The internal pipe tool is just expanding/ deforming the tube. Now there is no turning back.
I am afraid to hit it with heat because I figure it was going to ruin the intake manifold gasket. I would like to avoid pulling the intake if at all possible.

I would appreciate any help on this one.

Thanks.