I have a standard doghouse fan shroud (which I want to retain so I can use the air flaps and thermostat) Question is can I fit dual 36mm Weber IDF's? Who has done this successfully?

Yes - they will fit

You may want to add some "windows" the the side for access to the mixture screw and spark plugs

have a look at my thread here
https://forums.aussieveedubbers.com/viewtopic.php?tid=36756&page=6#pid964487 

Yes they fit, I have a set of 44IDF's in a 60 beetle that originally had a 36 horse power engine, I can still change the plugs without cutting holes in the body, just takes patients and the correct tools.

Thanks guys