Ever since putting a TPI/Vortec into my 89 truck I've never had the engine coolant return thru the TB due to too lazy to put a new gasket kit in, and also had the heater hose coming out of the Stewart water pump-old style. I know there are advantages to keeping the charge air as cool as possible, but living in Canada poses some other winter conditions- I haven't had any problems so far but as time goes on I find myself moving closer to stock configurations to limit divability problems. As I understand it- icing problems would happen around -5 to +5 deg C (around freezing) but deep winter dry conditions shouldn't have an affect either. Should I return the plumbing to factory. I'm putting back the 195 thermo from a 180 as well.

If you aren't worried about the couple of extra HP and it sounds like you aren't you should hook it up.