The Cline regulator's internal parts are not unlike those from the regulator side of a Walbro chain saw carburetor. I understand you can use the Walbro parts to repair one. The body of the Cline is plastic.

The Iron Bay has a diaphragm like the Cline but the valve part is made like a Schrader tire valve on your car tires. The body of the Iron bay is Aluminum.

Muffler pressure with Formost check valves in the pressure lines should be adequate for your pressure needs. I would use at least two engines for pressure. You can get the check valves from Tower.