Part of running a single shared throttle shaft was for a super clean look- like how datsun_tokyo linked above has it.
I also still haven’t decided on the manifold- but was planning on the TWM one- seems to be the cleanest and allows me to run without all the linkages.
That car is one of the main reasons I’ve even considered this. I have been in touch with him- unfortunately the language barrier is tough. Might need to recruit an old autox friend who is in Tokyo now to translate. The owner of that car did express that he much preferred the HSRs over OERs and that he was never able to find the right tune with OERs. Looking back through his thread he had PHH 50s on there at some point - but that is a very built engine - 3.1 I think with custom head etc.
Did a little more digging and thinking on this last night - I think mechanically the hardest part will be the common throttle shaft - it looks like each carb has 3-5 holes on the shaft. 2 for pins for to hold the throttle stop and accelerator pump levers; at least 1 maybe 2 for the return springs; and the main threaded one for the slide lift. With some patience and precise measurements it’s shouldn’t be to terrible, but not a cheap if you mess one up and have to start over on a new stainless shaft.