I haven't had time to cut a flange in half to see where I can drill and where I can't, but I hope it will be a simple matter of drill and plug. Like carburetors are made (now I'm dating myself). I hope to simplify the path after I see the profile.
With the path shown above, I think only one plug would be needed. But since there is so little space between the end of the IM shaft and the flange surface, It may be required to recess the snorkel into the flange surface a little. It is very thick in that area and a trough could be cut for the tube without weakening the flange I hope. I think the snorkel will also have to be a high grade rubber tube in order to get the flange installed.
Edit: Oops, correct, make that 2 plugs (good-eye James)