It's probably a tad low, I had a leaky cap an just replaced it without topping off. I don't really like the one I got from the LAP so I'm thinking about ordering a AC Delco one so it hopefully fits better.I had a regular hose barb on my 350 in the '94 C2500LD, and the heater core gurgled. A while later I noticed coolant trickling down the front of the driver side head from a failed intake gasket. Once fixed, no more gurgle..
Shouldn't be any gurgling in there unless there's air in the system.
Richard