I think I have one CT1 sealed beam left. (NOS)

Probably more for someone doing a high end restoration... I wouldn't waste it on a budget build.

Agreed.

Be really careful when you remove the clips - wear eye protectors and hold on tight to them with a pair of pliers! 

Hello - I'm the same situation and following along, and reading up on some other conflicting posts on this topic.  My original reflector is flaking away inside, so definitely interested in the more modern 5 3/4" sealed cycle light.  But its bigger than the original CT1 light....will it actually fit with the modern clips inside the bezel?  And what to do with the visible L/R adjuster screw?  Is there room inside the housing to secure it so it looks correct but doesn't move around?  
With no adjustment, is fine tuning of the beam possible, or necessary?  Shims?
Thanks,
Joe (also with a '70 CT1B)

I use a Napa 4020n it fits my Ct1c 

Or common 5 3/4" H4 reflector with clips. Use 6v 35w H4 bulb.  Adjuster is no longer used or needed.  Later models didn't have adjusters at all.