I was thinking of extending the travel on my Grizzly G0602's tailstock. An extra inch of travel would really be convenient. If you download your machine's manual from Grizzly, you'll have a decent exploded view of the tailstock assembly which will help you plan the mod.
In short, I figured I'd have to turn a longer lead screw, a new quill, and two barrel extension blocks: one for the front of the tailstock and another for the rear.
Lead screw:
On mine, there is the leading threaded part, followed by a shoulder, then a mostly unthreaded portion which is only threaded at the far end for about 1/2" at the very end. That *could* be replaced with a long piece of all-thread using a fender washer and nut to substitute for the shoulder.
Quill:
You'd obviously need to turn a new, longer quill and taper the ID to match the original taper on your machine. Oh, and finally, tap the end to match the lead screw.
Barrel Extension blocks:
You might just get away with on for the front. Or, you could add a second on the back portion of the tailstock. Mine is mostly square shaped, so it would be trivial to machine the blocks from some .75" or thicker aluminum stock. (There's enough room between the square shape of the outside of the barrel and the round quill bore to drill and tap a mounting hole each of the four corners of the extension block.
The front block would need to be bored to clear the quill taper, or included in the taper bore (prettier). The rear spacer block only needs to be drilled to match the existing lead screw exit hole.
Oh, and you'll probably need to mill a keyway in unthreaded portion of the lead screw since your quill wheel probably requires such.
-Matt