noisy gurgle in the heater matrix? sounds like you have air in the system
have a try at bleeding it out as it can cause localised overheating and loss
of water through the overflow.
Open the heater valves and remove the header tank cap and top up. Next
squeeze the top radiator hose a few times to expel any air caught in the
radiator top casing I used to also loosen off the bleed nut on top of the
rad untilfluid ran back to the top. then with everything in back place
remove the top heater hose bleed plug off the header pipe and give the  top
hose another gentle  squeeze your header tank should cause the header to
fill it usually takes a couple of attempts to get all the air out. If you
are lucky that may sort it .
If you have a failing head gasket running a warm engine at high revs will
blow water out of the header  and often leave the system still pressurised
after it has cooled .The trouble with the V8 is the number of pipes  and
clips which can cause small leaks which evaporate and defy detection I still
wonder if a ' UV black light' would show contamination by the flourescent
dye they put in antifreeze
Derek