8 3/4 vs 9 3/4

I'm worried that my new 440(500 HP Plus) is going to be to much for my 8 3/4 (489). I drive it hard but never thought much about it with my 383 since I did'nt run slicks but that will be changing. I'll get to the point. Anybody out there ever narrow a truck Dana 60 to fit an A body. How much did it cost and where you happy with it. A new moser goes for about 3000 fully loaded ready to bolt in. I have the wants but i'm not spending that kind of doe. I want to do it for around a third of that. Can it be done. I realize there are a lot of variables that need considered, so please let me here your opinions oh wise ones. I have a dana 60 from a 74 3/4 ton Dodge P/U lined up for $75.00 complete from break to break. Its a 4.10 with limited slip. Seems to good to pass up and sounds like a good place to start for my Dif. Project. Thank for the help.:dontknow: