I'm also large framed, 6'2 and over 300. I didn't know about backplates initially. So while trying on multitudes of BC's trying to find a fit, I found that the manufacturer's seem to believe that 3xl bc's require 4xl lift capacities. The Sherwood Outback/Genesis Recon fit great with adjustability to spare, but only comes with 75 lbs. lift. If you need this great but I dive mostly in Florida with a 3mil, 30lbs is plenty. 75 is a lot of Taco and hard to vent if you don't need it. I think the Oceanic Probe?? was the only standard jacket type that fit at all but wasn't comfortable. If you want to stay with the jacket sort of fit I would suggest the Transpac 2 and similar types that allow the lift of your choice and usually a little extra adjustability. I use other Zeagle gear but found the Ranger BC to be a bit "floppy" for my tastes. A friend had one customized that was large enough to try.
One shop had a backplate in stock, I tried it and won't go back to jacket styles.
P.S. You did not ask about wetsuits but I found Akona's were the only stock suits close to fitting. I wear a 4x and they make a 5x as well. Or did in the past.
