Most of the choke setups I've seen like that have a "stove" heated by the exhaust that the metal line hooks to. Just butted up to the manifold, I would think it would not open fast enough to comensate as the engine warmed up. You might be able to improvise by adding a bit more tubing and taking a wrap around the ex. man right where it comes off the port. Hopefully then you can rotate the thermostat housing so you have choke and fast idle when it's cold but it opens quick enough that it won't start loping as it warms up. Most parts houses used to carry kits that would convert that type choke to either manual or electric, but I don't know if you can get them any more.
