Well found. That looks very promising.

Finn, I'm lovin the way you do your mockups with CAD.  Wish I had that particular skill set.  The carb is way cool also.

A few years back I did some tests to see if I could pick up some flow by elongating the manifold holes and raising up the rubber manifold.  The port by design is 42mm but my carb is only 39mm, so that gave me about 1.5mm difference on the radius.  I figured I might be able to pick up some flow by raising up the carb all the way to the top edge of the port.  If it had merit, I then planned to grind the top of the port about another 2mm and raise the manifold up some more.  That would have resulted in the carb entry ending up roughly 3.5mm higher.  There was enough overhead room so that the carb could have been raised up that much without the frame interfering.  I filled in the floor with clay to try and maintain a favorable port entry.  I was never able to finish the testing.  Just got sidetracked with other stuff.

It lost a little flow on the first couple of attempts, and then I started fiddling around with other stuff, but I have always felt raising up the carb would provide a better shot at the intake valves.  You might want to try that approach first since it won't result in a permanent change to the cylinder head.  I think my first few tries were flawed.  I had too much clay build up on the walls of the port.  I believe that if I had confined the clay buildup to the floor of the port it would have been much better.

This picture should give you an idea as to how much I was able to raise up the manifold.  See the bolt impressions in the manifold flange.

Someday, if I get energetic, I want to try this again.  

I don't think I have the skill set required to do what you are planning.  That angled carb will require frame mods, and the seat will have to be raised significantly.  Setting up the airbox/filter will also be tricky.  If you can pull all of that off you should definitely see major league improvements in flow, even with the miniature 34mm valves.

Why don't you try testing the concept without doing major surgery to the head, similar to what I tried?  You might be able to achieve some very good results.  It won't flow as good as what you have proposed, but it will be way less invasive, and the exhaust port will have an easier time keeping up with the intake.