Any question answered...

You current set up has a top tube + stem of 63cm (57+6) which you describe as too long. To cut that down to 60 using the 12cm stem which would be considered normal on a frame of that size would need a 48cm top tube

well.. that's just insane.. and would probably look daft too. Thanks though!

I think I'm gonna have to get something smaller and put a long seatpost in