What's the OD on the studs? I've restored many classic engines in my time. I use FOX wedges on heads, they are very thin steel wedges used in engineering for that very same job! Also to clean out the corrosion down the studs you can use COPPER TUBE.....! If you can get tube the same ID for the studs and OD for the hole. In one end of tube cut jagged "teeth" with a hacksaw. Nothing fancy as you will need to repeat a few times in the process. Either drill a hole in opposite end or attach some form of handle, I use small bar through the hole, an Allen (hex?) Key is fine. Then just slip bar over stud and rotate to cut down between the stud and hole! Works great on alloy housings with steel studs! Thermostat housings etc.
