https://www.summitracing.com/parts/bsp-90820/overview/

I'm pretty sure this is the one I bought for my small block. I haven't run the engine yet to see if it seals. I did notice that once the housing was tightened down, the thermostat was still a little loose. The stock thermostat housing holds the thermostat tight. Not sure if this is a big deal or not. I did add a little sealer to the perimeter of the thermostat and it doesn't move now.