Hi Claire!
I have both an ocicat and bengal mix. I personally prefer raw diet and I think the kitties do too - but my partner is a little less enthused, so we do both. I did a lot of research and this was my favorite site:
http://rawfedcats.org/nature.htmMy cats won't eat the raw bone, so I supplement the raw meat & skin with Felini Complete - it's a simple powder that you sprinkle on the food and mix with warm water. I don't have a grinder - so I cut the meat by hand & freeze it in tiny 1-portion containers. With a good grinder you can incorporate the bone and wouldn't need to add the powder (just never give them cooked bone - only raw is safe).
I started them both off as soon as I got them from the breeders (16 weeks) and they took to it immediately. As yours are older - you might need to transition. Mine eat chicken, turkey, duck and beef (duck seems to be the favorite). I cut it into very tiny pieces when kittens and bigger pieces as they got older - if they're not used to chewing raw meat, you want to start with tinier pieces. As their jaws get stronger, they'll be able to handle larger parts. They also like chicken hearts - but you want to limit the amount of organ meat you feed them to about 5%.
I like the raw diet, because the cats seem to regulate how much they eat. It's a little more work for me - but the price is actually less than a lot of the premium food and I love how healthy, shiny and muscular they are!
Hope this helps! :D