If he's willing to eat raw meat already that's a great sign. Some cats are super picky. All I did to switch mine was offer her some of my ferrets raw and figured out what she would eat and what she wouldn't so for several months she got raw some days, canned some days, once I got her eating several proteins and organ meat I dropped the canned. She had no problem with chunks and bones right off the bat and she was at least 13 when I switched her in 2010, had put her on canned a couple years prior after years on kibble. My girl is picky, will not touch or pukes back up most hooved animals but any poultry she loves, chicken, goose, duck, grouse, if it's got wings she'll eat it and she gets rabbit and mice as well. I don't supplement or add oils/veggies/etc. It seems like a lot of cat raw feeders do ground, I find it way messier and my cat doesn't like it much either, I use a little to get variety into her but generally feed chunked meat.