There are some WT local populations that get large also, 5-6ft in length or more, it has to do with originating closer to the equator, some at higher altitudes etc. Tanzanian WTs get larger, Sienna Leguaans (sienna colored WTs) get larger (5ft or so). BT males have grown to 7ft 3 inches, females get large also (Ill find out in the coming years how big they can get as my BT/WT/WT cross is now 6ft 3inches long and 28lbs, yet she is under 3 years old). Sobek has the physical size of a BT, some pattern from both, and colors from both. My male BT/WT cross has the physical characteristics from the banded WT (his father) as size goes at 4ft and over 10 lbs at just under 4 years old. He has the build and body shape of the banded WT except the head is a bit different (like a BT), he also has colors and patterns of both.
Argus can get big also, heres a good friends male at 5ft and 15lbs, the female here layed an infertile clutch before he brought her home from her former owner (he was showed the eggs), shes 3ft 2 inches and alot lighter.

This is a few months old pic of my big female cross..

This is Blaize, a friend of mine raised him but due to neck surgery says he cannot properly care for him as he would like to, hes giving him to me after I can set a cage up for him, Blaize is around 2.5 ro so years old and 5ft about 15lbs..

This is a male 3year old cape banded WT named Zeus, hes a bit more than 3ft long, hes a Frank Retes baby.

This is Shadow my male BT/WT cross..

Unfortunately it is almost impossible anymore to get CBB WTs except from FR, or BTs from a handful of others, true CBB animals are expensive. As far as CBB bosc good luck there are a few with eggs incubating now, lets hope for the best, they will also be very expensive (a few hundred $). Its worth the price though, the cage Im building for Sobek as comparison cost me at this point over $600 in materials, not including lighting, dirt, water dish, etc, I expect it to cost around $700 when done, not including my time. The cage is 22/32 plywood with .090 FRP lining it, its 10x5x4 (had to reduce 2 measurements to build it in my new houses basement and get it up off of the floor). This new cage will have at least 2 basking spots with 4 bulbs each on adjustable height chain set-ups. Right now theres wood and FRP piled everywhere.