Technical Thermostat Neck Help/287 V8 55 Pontiac

I spent the better part of the last month replacing my water pump, thermostat, hoses and fluid including rebuilding the radiator. A few days after all this and enjoying a cooler running car, my thermostat housing cracked. It wasn't from overtightening, I made sure of that.
Question is: I cannot locate a replacement neck anywhere. Does anyone know if another make/model will work? The neck is straight with no curve. Pic of the damage

 

can you take a better photo and post hole sizes and distance. I can look through my stash.

 

Appreciate it; do these help? End to end and center hole to center hole. The bole head is a 9/16 and bolt opening on the neck is 3/8 diameter. The top water neck opening is 1.5" diameter and the base diameter is 2 11/16.

 

Found one locally this morning, thank you for your help @tb33anda3rd !