I have fit a 325 50 15 in the stock wheel well......you will fit a 10.5. You will need to cut the bump stops out and do a little work with the swing press on the inside and possibly trim the lips depending on how low the car is.
I'm running the 295/55/15 et street radials which are a true 28/10.5 and they clear fine. Like mentioned I trimmed the inner bump stops a tad. I also did the BFH mod to the inner fender just for a litle extra clearance but it wasn't necessary.
My rear is narrowed 3" per side, 6" overall. the wheels are 15x10 Bogarts with 5" backspacing. the normal 15x10 wheel on an uncut rearend needs a 7.5BS so technically I needed a 4.5BS. I went with a 5"BS to help pull the large 28" tires inside the quarters a bit more just for looks.