Overheating during cam break in - help

Just by feel

The cam will be fine.

What does that mean;"by feel"?And what do you mean"it shuts itself down?
-You know most guys cannot feel temps in excess of 135*F right?That is to say, we cannot keep our hand on that hot surface for more than a second or three; so I for one couldn't tell you if it was 130 or 180,or 220.You need to get an IR gun.Honestly tho, that's a pretty poor idea to not have a working temp gauge.
-The hole is just a bleeder. It can go anywhere on the flat disc,between the gasket ring and the pellet ring.You can accomplish the same thing, by filling up the engine through the stat house. When the liquid level comes up into the stat house, put it back together, and continue filling the rad until it is just above the core-tubes. Leave the cap off. Then as the engine comes up to temp,and when the stat opens, the liquid level in the rad will fall. Top it up again to cover the core tubes and watch for coolant circulation.

The backfiring during cranking is probably fuel related.
If it actually shuts itself off, and backfires, it either flooded itself to death, or ran out of fuel in the bowl, which could be the tank vent is not working, or the low-speed circuit dried up.
Well there is one other possibility, the valves ain't closing no more. With a cam change you always have to check the valve lash or lifter preload. If you bottomed the pushrods in the lifters, when cold, then as the engine warms up, it could, that is,could, happen that the valves no longer close. That will for sure cause stalling, and, backfiring during cranking.
And of course it could be electrical, but I doubt that.....