So, I spent some time checking out this topic:
I took the Bristol 32 BI carb, a Porsche 356 32 PBIC and a Porsche 356 40 PII-4 from my stock,
As well as tool P-78. This is what I found:
threads: interestingly enough both German 32 PBIC and British have metric 8x1.00 starters so the attachment for checking the bowls would be the same. 40s have a different M11x1.00 that matches P-78 tool.
So in theory you could machine an extension M8 to M11 to use the tool. There is an M7x1.00 extension available, that is for the zeniths also used on porsches 356. At this point I also had a look at the factory preA and A model workshop manuals as those are the models that used the 32 solexes.
The method for adjusting the fuel high in the bowl is the traditional which involves taking out the top cover.
I also checked the potential attachement to P-78 to the 32's....the lowest level indicated by the tool will still be too high compared to the maximum that the 32 will need. So the tool is not usable.
32s have way smaller bowls compared to the big, deep bowls of the 40's needed for the S-90/SC/912 series and P-78 was design for those clearly. Also there is a good reason for this tool as 40s do have an outside bolt to regulate the float high without taking apart the top cover.
So, long story short, P78 won't work and in fact won't make much difference as you need to remove
the cover anyway.
Ignacio