[Daves55Sedan]

I'm not so sure it would be a good idea to plug both ends if the heat riser tube inside the manifold. If you did, you would trap heat inside the tubing which most probably would cool faster than the surrounding cast iron intake manifold causing condensation to occur inside the tube. But I'm not an expert on this, so let more intelligent heads among us chime in.

Added: if the tube inside the manifold is known to have a hole in it, exhaust gases will get into the tube and blow out the ends, so by all means plug both ends if they are no longer used.

As far as the copper tubing connection to the bottom of the choke spring housing, I would remove the copper tube and screw the brass fitting back on the housing leaving the copper tube hole in the "cap" without plugging it, but again, lets hear from others more familiar with auto-choke conversions. The theory is, since now there is no need to hold heat inside the choke housing, it might not hurt to let it breath a little.