"Thermostat cover"??????
Are you referring to the choke stove, the part that supplies the hot air from the exhaust manifold? If so, there are aftermarket replacements available that clamp to the manifold with a couple of hose clamps. If you've got the remote choke assembly that mounts in a well on the exhaust and connects to the carb linkage with a rod, it's impossible to convert to an electric-heated unit anyway. Fix what's there and do it the right way the first time. It's not difficult to drill out a broken-off bolt and re-tap the hole.
Jerry
