Question on PTO driveline for rotary mower

I have my grandpa's old Ford 22-60 rotary mower/stalk chopper.  With me it enters its 3rd generation of service.

 

I need to replace the PTO driveline.  The 6 splined shaft that comes out of the mower gear box looks like it's a 1 1/8" shaft.  Are there any PTO shaft drivelines where the implement size is 1 1/8" and the tractor side is 1 3/8"?  I have not been able to find any so if not, would I be able to put a shaft adapter over the mower shaft to bring it up to 1 3/8" so I can then hook a PTO drive line up to it? 

Question on PTO driveline for rotary mower