The T.K.O. 600 Won't really give you any benefit over most 5 speeds. It has a .68 and .82 overdrive models. Not to mention, you'll need one with the forward shifter. An NV3500 or NV4500 would be a better transmission for your truck, and alot easier to come by and have a .73 overdrive.
The 4.57 rearend isn't the "end all" like most would suggest, With and overdrive trans, it's a good setup. Some of the newer trucks come with a 4.56 rearend. With a .73 final drive ratio transmission and 31" tire, you'll be cruising at 2100 RPM at 60. Not too shabby.
More advise: Don't bite of more than you can chew. I had big dreams for my 3600 truck. I've had to learn along the way to keep it simple. Whatever path, you choose, stick with it. Don't change your mind 100 times along the way.
