I am glad to support such a unique project and love to see it and you, of course, at Glemseck 101 this year !
It should work with the oil return.
I can only see the diameter size as an issue. As there are 750 cm³ displacement this amount of air needs to go to the catch can without giving to much pressure to the oil return of the turbo.
Sure the remaining oil pressure on that return line is much higher than the air pressure pumped by the engine. That means the oil will drain down to the crankcase, but is still under pressure.
That makes the engine ventilation even more important.
To avoid that, my first idea is to double the size (area in mm²) of the crankshaft ventilation.
As that is related to boring and swarfs I suspect it can only be done with the crankcase split into halves.
I don’t have any experience with a changed engine ventilation system, these are just my thoughts 😉