check for burrs on the head???
using the same head......was the block known to be good? maybe it could be cracked?
ummm hey check this. the pipe that bolts on the bottom of the head, for the heater core. is it all tight?? maybe theres a possible leak coming from there. I got mine plugged with a pipe plug and the damn thing leaks. I should have put some teflon tape or thread locker in there.
just a suggestion...because the drip coming from there would be pretty much exactly where you would describe yours is coming from. just put your finger on the bottom of the thermostat housing area and see if its getting wet. i had a hard time seeing the leak coming off my head