Those look like 8" wide wheels to me, it's possible they could be 10's but with how well they fit in the fender wells I kind of doubt it. They definitely aren't 12", they just have a small backspace so they look wider. They could be running those 285's, but if you're wanting to run those on your 48, I wouldn't want to steer it in a parking lot with an 11" wide tire if you don't have power steering. It would also cause it to want to wander quite a bit on the road as well.
I'm thinking they're probably 8's with a 265 or so.
Here is what you asked for, but I don't think that will give you the look you want without a custom offset. I also think you'll have a hard time fitting 10" wheels in there without modification, unless you don't mind them hanging out of the fender.
I'm running the same size tire as that 285/70 on 10" wheels on the back of mine, and my dad has those 285/70 BFG tires on the back of his '52 Chevy on 10" wheels. Both are tubbed for clearance, but they're also both lower as well.
