Yes, shimming the column is the only way.
The power drawbar I ordered from Greg has a longer drawbar in it so I'm going to hold off on the length for now. I think I'll have to modify his baseplate to get it to fit the 833. We'll see, though.
I made a lot of chips today. That thing is crazy messy! I went to the aluminum scrap yard and picked up a block 9" x 9" square of 5/8". My plan is to replace the cast iron ring around the spindle that they used for the stop. The ring was put on before the spindle so it has to be cut off. I'm waiting to do that until I have my aluminum one made.
I tried boring the ~3.5" hole with a boring tool in the mill. What a PITA. To do that I had to figure out how to clamp it to the table. The
clamps (they're pretty slick) I bought were too big for the T-slot so I had to cut each of those down. Of course, I discovered my good fit was a bit too tight depending on which slot I used.
I gave up on the boring tool and chucked it in the 4 jaw on the 1340GT and made quick work of it. Having Mark's proximity stop was great so I didn't have to look from the side to see how far I'd gone in. The next step was to cut the plate in half with my Makita carbide blade. Of course, the block was too big so I had to take parts off the saw stand and use clamps to get it cut. Then, I spent way too much time milling the halves down to width. I should have but it back on the saw but it was cutting slow so I may need a new blade. Those things are spendy.
So, I think I've got it all done and will double check it all tomorrow. Then, cut off the cast iron ring with, I'm guessing, a cutoff tools in the dremel. We'll see how that goes. But, once it's on the mill then I can figure out how best to mount the stop and DRO and then order a new faceplate.
I'll post pics tomorrow of the new collar once it's in place.