[TR] TR 2/4 block drain petcock

[Angelo Graham]

Good day listers:
Has anyone used one of the newer ball-valve petcocks for the drain 
petcock in the side of the TR2/4 block? Wondering if a ball-valve can 
be sourced for this application? The threads look like 1/2" std. pipe 
threads, but I gather that the valve body has to seal against the 
block with a gasket or "O" ring. Haven't found anything that might work.
The original petcock on my block has pretty well had it with the 
spring corroding to nothingness. Thought that a ball valve might be a 
good substitution.
Thanks in advance for any advice.

Angelo Graham