I decided to sleeve the original rotary valve for this motor.  I did it for my '48 and still had enough material to do another one. The early engines had a unique rotary valve unlike the H engines.  I have been told it was an effort by Simplex to help with low end power.  I also learned that this engine will run with an H rotary valve.  None the less I went forward with restoring the old one. 

Fortunately, the block measured quite well and by sleeving the valve I will have a running clearance of .0035 per side.

I have two of the valves so that helped with set up and location of the slot and hole.  I made a shaft to mount the part for machining.  And instead of just using an endmill cutter near the slot size I used a quick program to actually mill the shape of the slot out.  This allowed me to sneak up on the size and not take just one bite at it.

Last picture is a page from the early manual.  Shows this style rotary valve.

You just gotta love it when a story comes together!

I think this would be the right one for both of your bikes.

Welcome to the rocker clutch gang!   Post some pictures when you can. 

Saturday for me!  Jim Lokai will be there Sunday morning.

Glad to meet you!  Have fun with your Simplex.  Can't wait to see what you have!

That is a sexy sparkplug clip!