Any advice on sizing up a SteelHeart?:)

Hi all, I’m hoping to get some confirmation that my measurements aren’t way off, or just general advice!:D I’m aiming for a SteelWorxx SteelHeart with a PA lock of 4mm. The integrated locking mechanism seems essential, and I think I’ll go ahead and choose the steel ring too! Right now, I wear a CB6000 but feel it’s slightly oversized, while a CB6000s feels just a touch small. I don’t care for how rings tend to chafe, and my PA seems underutilized in a CBX. With the CB6000, I use the middle ring which is 1 3/4” (44.45mm). I’d prefer not to go larger, and since it’s a narrower ring compared to others, I think dropping down one size to 42mm makes sense (it seems like a very common choice). I’m fairly confident that’s about right! The CB6000 has a length of 3 1/4” (82.5mm) and width of 1 3/8” (34.9mm). I’ve been experimenting with a vernier caliper:lol: (which is pretty handy for this sort of thing) and found that a tube width of 35mm works well, just like it did in the CB6000. Now down to length, which might be one of the trickiest parts to estimate. The CB6000’s length feels a bit excessive when I pull back, which is annoying. Considering I’ll have the ring on, my current measurement sits at 72mm (fully soft but not shrunken up from cold haha). I’m guessing I probably want somewhere between 76mm and 80mm, though I’m not entirely certain! Also, would it be worth opting for an anatomical ring? It looks much nicer to wear. Thanks in advance for any help! Looking forward to reading your replies! ~Indigo