What you've got right now is enough for a slaughtercult+blood host, so I'd reccommend running that. Maybe buy a couple rhinos for zerkers, and you can probably call it a day. I would make the skull cannon because
str 8 ignores cover is tasty

. Fleshounds are good, probably wanna bring a jugg lord with them. I'd get more bloodletters for cheap troops that can do more than cultists. Bikes for fast melta/
plas, maybe a couple dinobots (forge/maulerfiends) for long range support or in your face power fists.