In my Super8 projector I am using this lamp, in my opinion with good results.
As very well says @PM490, when using a projector we are limited by the available space.
This lamp is small in size, very easy to use, powered at 12V with the same power supply as the stepper motor. As a switch I use a software-controlled ULN2003 chip.
In my case, I also have the advantage that they physically sell it in a store in front of my house and it only costs €1.35.
I have searched on ebay and the closest thing I have found have been these lamps:
https://www.ebay.com/itm/234561455572?epid=21020983381&hash=item369cf3c5d4:g:FhUAAOSwBrReSpUV
In 16 mm I don’t know the result they can give. Perhaps it is worth trying them, if the results are unacceptable, which I doubt, there is always time to try something else.
Regards