Good information I will address these items,, as for hot spots in head it is a valid point,, one the the big ones is trapped air pockets some heads will boil the coolant near the exhaust outlets . bleeding the head is something I do on the motorcycles,, difference in thermal expansion rates of block to head in my turbo Chrysler resulted in premature failure of head gaskets,,, in the 60's we used pure copper head gaskets on turbo bikes,, better heat transfer cooler heads,, and running 10.5 compressions copper gave use better sealing. I forgot about the cool down thing,, very good point,, will do !!!
one thing I ran into on moded bikes with turbos in the 70's,, after the oil leaves the turbo we had to use a large diameter oil return line in to sump,, the bearing and speed of the turbo would froth / whip up the oil and create bubbles.. we added stainless steel wool or wire mesh,,at the end of the return tube to break down the frothing,, net result was good constant oil at pump pick up point,,no cavitation due to bubbles in the oil ,,