Responses
About gangster uke, maybe you could try Saezuru tori was habatakanai and Nights from Yoneda Kou if you haven't read them before.
http://www.mangago.me/read-manga/kamisama_no_uroko/
I hope I could help you (づ￣ ³￣)づ
Any yaoi or shounen ai manga where the uke is a playboy or a gangster. Thanks in advance!!