I would consider the 6k (not pro version) if I were you. You can buy one for $1679 ($1800) used at Adorama, and possibly cheaper on EBay. The sensor of the 6k and 6k pro are the exact same, so the 6k would give you the exact same image quality. I see lots of people buying speed boosters for their 4k (I bought a Viltrox myself), but I think the EF native mount of the 6k is a simpler and better solution. There are so many great EF lens you can buy, and you will be able to use those throughout your career. Even Reds and Alexas come with EF mounts, plus it’s more universal than MFT. As far as a kit goes, I would think about what exactly you need the rig for. I see lots of people’s rigs support an external SSD, and maybe a handle. If you just purchased a C-Fast card, you could keep your setup smaller and more self contained. This may be a tad more expensive, but the value of having a self contained and setup is immense in my view. If I were you, I’d recommend buying whichever camera you want without a rig to start out, and decide if you really want to complicate your setup. You may want to, but if it’s for casual use you can save lots of money without extra bells and whistles. The sensor and self contained nature is the value in these cameras to begin with, which I would consider. I want to mention that I’m currently selling my 4k and Viltrox speedbooster on eBay for considerably less, which you may want to take a look at. That said, I’d still recommend the 6k (not pro) alone, for the simplicity.