If the heater is working it's likely pretty close to OK. Hard to tell without the temp gauge. Can you borrow an IR thermometer to see what's really going on?
Try to bleed it on an incline. Check the rear temp sender in the head for a loose connection. Might be the cluster too, the little rear nut has a habit of working loose.
There's a bleeder passage on the thermostat housing...did you use silicone or the OEM paper gasket?