I was filling up the coolant per the procedure in the Haynes manual, and after the thermostat opened up when I topped it off some coolant would bubble up and out of the filler neck. A friend told me it's just the pump pushing coolant through the neck and some of it spilling out, but I'm just making sure.

Here's a video:
http://www.youtube.com/watch?v=_zFb7DfJXwA

After filling it I put the fan and shroud on and drove it around for about half an hour with no issues, Temp went to just below halfway on the stock gauge and stayed there.

 

Perform the same test with the engine cold. If it is still belching coolant, then you may have an internal o-ring leak. However since you say you aren't experiencing heating problems nor are you losing coolant, then there's probably nothing to worry about. With the pressure cap removed, coolant in a hot engine will boil.

 

I've filled some very temperamental cooling systems exactly like that. It's a bit of a paint, but it seems to work every time.

 

Awesome, thanks guys! It didn't do that until the engine came up to temp and it's a fresh rebuild so I think I should be ok, so stoked to drive this thing!