OK Understood
So cheaper solution will be UN1 renault gearbox fr many reasons
1/ you can find those (as base very cheap )
2/ there are so many possibilities to increase reliability because many updating parts are avaible ( this UN1 is also used by GT40 builders
Depending on how much Hp you are planning to get fron the engine you can also use a VW cox as a base and then update the gear box as I did for the lotus 23 so this gearbox replicate an Hewland Mk8 ( you can easily found second hand side plate which include casting provison for inbord brake
And you could also drive the alternator thru the end cover doing a very very easy mod ( eventally could help you with some engineering for those mods)
Pro for this solution is you can easily with very reasonable cost relicate similar setup of the pic you posted ( cv joints , brakes and alt )
Con ; power will be limited to 180 Hp max
So another solution for200hp and more will be the 911 early 915 gearbox with ( if you have access to pattern and foundry ) bespoke side plates done
( could friendly help also with engineering !!!

) cv joints are similar to the ones in your pics
I used one of those on the 907/8 project and am more than happy with ( fitted an LSD and an hydraulic release bearing )