Hybridguitarist

so I have a 95 Acura integra gsr B18C. I put the gsr crate motor into my 4 door Ls that had 200k miles. I replaced the thermostat, tested the thermostat before I put it in cause some time new ones are faulty. Replaced timing belt, water pump, all heater hoses and clamps. I did not change the head gasket, and I know I should have since the motor was out. I Bled and burped the cooling system, how I did it just in case someone want to know how I did it. I opened the bleeder pored coolant in till I saw coolant come out of bleeder, closed bleeder then filled the radiator and reservoir, and I used the spill proof funnel. Started the car let the thermostat open up, kept the radiator topped of when fluid dropped in the funnel. let the fans come on twice and waited till there were no more bubbles coming up. Put the radiator cap back on. Checked the level the next morning and was at the neck of the radiator indicating no leaks over night. Did the spray test on the radiator while at operating temp and only one small spot on the upper left wasn't evaporating the radiator. Radiator is old but seems to be functioning fine. So I went out to test drive it and the heater gage never went past the 10 o clock position till I opened it up and did a pull and It went to the 2 o clock position. So I pulled over and checked some things. The over flow was almost to the brim and so I dumped some of it into a jug afraid it would burst or something. Then I continued to drive and the Guage stayed at the 10 o clock position, but I pulled over again to check the overflow and it was almost full again but not as much as it was after the pull. I then noticed that there is a little bubbleing in the over flow. Not boiling but air bubbles. I can't see any noticeable oil in the coolant, or coolant in the oil. It's 41 degrees currently and the smoke out of the tail pipe seems like it could be a little white but it is cold outside, so I don't really know. Is there any direction I should go with this before I think about h/g? Any help with this would be greatly appreciated. Thanks HT