Hard to tell from the picture, but the tire on that truck looks very small. I would guess 225/50/15 or something around there. It also looks like the truck has airbags.
The size you mention 295/50/15 is very wide, and it is about 1/2 inch taller than a 235/60/15. I am afraid it would rub in front with a 4-inch drop.
I ran a 235/60/15 with a 5/8 drop on my truck with stock wheels. The front tires were very close to the fender lip, I would not want to go any wider or taller.
Here is an old picture of my truck:
A 5/8 drop is basically like a 4/6 with a 3" spring in front instead of the 2" drop spring, and the back you get the extra 2" by adding drop shackles. You also need a bigger notch for the 8" rear drop.