Thermostat Housing Leaking

I have a 70 340 with the Eldebrock Performer RPM INTAKE.

I replaced a chrome thermostat housing that had a slow leak. I replaced the gasket with a new one and switched it around from back to front. So it leaked in the same spot.

I went out and bought a Billet Housing with the O ring. Put it all together and low and behold this housing was worse than the other. Out of curiosity I removed the hosing again and left the thermostat out and didn’t use silicone. Low and behold there were no leaks. So I removed the Billet housing and put in the thermostat and when I did this it leaked again. It seems that the thermostat raises the housing to allow air/water to escape and not seal.

I am at my wits end and lost my patience with this. Do I have to use a specific Eldebrock housing with this intake manifold?

Thanks in advance for any help.