As an introduction, the plan is to convert my 1835cc that I have build entirely based on the excellent advice from this forum, to ITBs.
There are a couple of reasons why I want to do this, but the main one is that I want to use T1 stock cooling, and then my centrally mounted plenum will not work.
The plan goes something like this:
I have sourced a set of 40mm ITBs from ebay for around $90, and I here is a shot of one of the pairs:

I plan on using a set of standard IDF manifolds, and these little babies in stead of fuel rails:

Then, today, I finally received a set of spigot flanges from a local motorcycle shop. They totalled about $50 for all 4.
The diameter is perfect for the ITB:

And the bolt pattern is quite a good fit to the IDF pattern:

There are a couple of issues, however.
The first is as Dale also points out, that the cc distance between the barrels is smaller on the ITBs than on the manifold, so I plan on simply separating the ITB, and then elongate the throttle shaft.
The other issue is that the inner diameter of the ITB and flange is about 8 mm smaller than the IDF manifold, so there will be a step that probably is not very good for the flow, so I will give that issue some thought. I have a couple of ideas,, not necessarily involving jb-weld

The issue with cable vs linkage is still open in my mind.
So am I heading in the right direction here?