I did it on my Krooley 8nj that I had in 36 and I tryed to sell. But I'm happier now.
first I bought one other 8nj to have the material to enlarge.
second I know a very good tailor that made it for 80$.
I have pics for people interrested.
if thavar fit well in 28, than go to 28 in shioner. don't listen people who always said "size dooooooooown" without read your message. your jeans have to be confortable, you don't buy an 150€ jeans to be not confortable...