Pipe Reducer 6" down to 2" 1

[Mandrill22]

I have a vertical schedule 80 PVC pipe, 6" diameter, 36" long with a male threaded NPT end. McMaster 4687T73. I'm trying to find a bell reducer to get it down to 2" or at least 4" so that I can put a cheap as possible valve on it (app below) Is there any reason I can't find one?

Alternatively, I could use the iron version of the pipe in the same size if that would reduce cost of the eventual valve.

Application:
The pipe is holding lead balls, total weight being up to 275 pounds.

 

[Compositepro]

McMaster does have these with socket connections. The unthreaded pipe is also much less expensive.

 

[Mandrill22]

Can the unthreaded hold up 300 lbs with just cement?

 

[Compositepro]

Cemented connections are stronger than threaded. A note in the catalog says to reduce pressure ratings 50% for threaded pipe.