Heat Riser 225 slant six

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This is what my empty heat riser space looks like. I’ve tried a heat riser off a 175 and a few other slant sixes. Regretfully, none of the ones I have fit this vehicle’s setup.

I’m at the point where I’m considering a choke pull cable but, am hoping to keep things original to the car.
A bigger photo including the carb might help in finding what you need. I think Pishta showed the proper choke assy. It uses a choke timer which I think I see in your photo. (but not sure). You won't need the cup that Wayne shows in his photo. That cup was used on an exhaust manifold with an opening into the exhaust. They were used from 1970-1972. For those reading this thread and are confused as to what some of these items are called......the heat riser is built into the exhaust manifold down close to the outlet. It has a weight and bimetal spring that operates a flap to increase backpressure and help warm up the engine. The parts Jimacuda posted are heat stoves. They also help engine warm-up by ducting warm air from the exhaust manifold up and into the air cleaner. A thermovacuum valve controls the operating flap in the snorkle of the air cleaner. All these parts should be used if you want the car to start up and operate properly at all temperatures.