the exterior part of the exhaust port of all the175cc barrels are the same size but different internally the D14/B175 just had an adaptor ring to take the larger bore ex pipe
but your one looks like it had been made the full large size without the adaptor ring
whether it worthwhile playing with modified barrels only you can decide

if its a D10 onwards barrel it should have a Dowel on the bottom right hand side of your 2nd photo which I cant see
the inlet is a bit stupid 38MM ? no carbs are that shape
think you would have problems with air leaks and would the transfer ports be upto that amount of flow
getting the mixture correct across the full rev range could be a real PITA
but you like a challenge