Everyone, all great replies - Thank you!!!
So, yes that got me thinking so got down and did some measuring... the 90s & 45s makes perfect sense!!
I do have a header tank mounted higher than the thermostat. The tank has a radiator cap, overflow bung, and a 3/8 npt on the side and a 1/2 npt on the bottom. I'm not running a heater in the car (Texas = a/c only), I could run lines off the water pump heater loop to the header tank, or would it be permissible to run a single fill line? There are 2 bleeders on the top corners of the radiator.
Thanks again.