The more variety the better, when it comes to raw. I'd suggest having at least 4 different proteins in a meat rotation. The exception being if the 80% portion would be canned. If that's the case rotate the canned flavors and only feed bone if you're doing it for the dental advantages.
As far as heart goes; my kitties all LOVE heart. Its like kitty candy in our house. Originally I fed ot because of the high amount of taurine (the harder - darker - the meat is thd higher the taurine content) but I feed it now because they love it too.
As far as halal/kosher meat goes...if you're trying to feed 80% raw you NEED to feed liver and a wider variety of meats than just chicken and beef. In a week my guys get: chicken, turkey, duck, pork, beef, and one 'special' meat like alpaca, fish, game meats, ect. Minimum. They have also eaten goat, lamb, llama, bison, elk, goose, quail, Cornish game hens, and salmon. Basically, if you want to feed mainly raw you need to plan for non-kosher meats and their storage.
Id suggest setting up something that your fiance is comfortable with before you really dive into more raw. Some cats (*cough* mine...and many others I've helped switch) will take to raw really strongly and refuse 'normal' cat food for a bit right after you transition them. It isnt crazy common, but it happens.
Also, sorry it took me so long to respond. I was on vacation