Right off the bat, I can tell you 50 pounds is twice the size of the average Basenji. But....
If you could upload a couple photos for us, we can try to determine if she may be a Basenji mix. One showing her standing from the side so we can see her basic structure (would be very helpful). Basenji's proportions are a rather square, so the side view allows us to compare the length of her legs to the length of her back. And one or two others would be nice as well.
Boy... I’m gonna say definitely maybe. She could have Basenji in there. Tail curl, chestnut color, white feet and tail tip and body build all suggest Basenji to me. Head shape, ears and overall size not so much. But that could easily be the other mix. She’s cute. What are her mannerisms like? Does she bark? Things like that...
She does bark, Usullay when excited.not for long though. Cudly, sniffs around alot when outside. She most definitely gets a scent from possible deer, fox,rabbit and gets excoted sniffing. Loves having her toy,ball tossed for her to jump to catch. Chews. She shows attachment to us, sad when we leave for work.
You might compare her to a boxer mix, they have that coloring and if the tail isn't docked it curves over the back, I have one that is part boxer and maybe basenji, mine has got the white like yours but is brindle instead of the brown, also weighs 50 lbs. very loving and very playful loves balls. So you might want to check it out.
IMO, there's a basenji back in her family - but something bigger too. She definitely has a basenji's eyes.
Not smelling like a 'dog' when wet is a basenji trait. If she smells like a dog, it does not mean there is no basenji in her, just that if she has that trait, it can be put in the 'basenji in background' column.
I am perhaps in the minority but in almost 40 years of breeding and living with Basenjis, I have yet to have one play 'catch' with a ball. Other dogs find them in the woods by the hundreds and carry them in their mouths, often to the disgust of their owners if they are particularly dirty (and therefore desirable).
My pack - never a one.
The color and the white feet and tail tip are the only 'basenji' features that I can see in this lovely doggie. Nothing else screams 'BASENJI' at me.
However, if it really matters to your enjoyment of such a super pet, you can always get a DNA test. Do let us know the results !