This may be silly of me but I've run into a slight cooling issue with my ol car. Its got a vortec block(newer than 96 I think) and heads. I recently installed a heater block off plate, msd box, msd external coil, and distributor. After doing this I've run into a overheating issue I would normally run 180 +-10 degrees and now it gets up to 180 and slowly climbs up and stops around 210. I usually see 10-15 mins of highway then a good deal of stop and go. I've got the timing set to 12 degrees btdc with the heavy springs and 21 degree advance no vacuum advance. I know the vortec heads and blocks require a coolant bypass so I made one where the heater core use to hook up and it helped a little but I still see high temps. I'm a little at a loss as to what else to do so any help would be appreciated.