Hey Laughing Turtle!
Firstly.......WELCOME TO REPTILICIOUS!!!!
Unfortunately us 'Brits' don't usually work in gallons when sizing our aquariums over here....But am I right in thinking that it's about 4 foot in length?
If so, I guess it all depends on what you're really looking for from a pet turtle/tort?
I'm guessing you want something similar to your Box Turtle, ie something that is as happy on land as in the water?
I reckon you should stick with what you know best hun....If you've only recently lost one after owning and caring for him for 36 years (They have an average lifespan of 40yrs, so if yours was already an adult when you got him, you must've been doing something right!

)
So why not just get yourself a young'un and give him the same love, care and attention that you obviously gave to Mr T! - You don't need me to tell you what great characters these li'l guys have!
The only thing I would add is that you get a form of UV for it (Forgive me if you already have this, but I didn't see it mentioned before) as it will need this as well as a basking spot!
As for your Q regarding the 'Chinese Box Turtle' - You should still be able to get one as long as it's captive bred as, as far as I'm aware they've ceased the import of them into the States....But don't quote me on that! Haha!
Anyhow....Good luck & make sure you post some piccies up when you get your new baby!