im using a flaming river column. Mine is 30" which puts it at the stock length. Upper dash mount seems to fit ok- prob. will need a piece of rubber around part of it to snug it up. The lower has no mount. Flaming river sells a large swivel mount-to fit any angle- for a couple hundred dollars. I decided to make one for mine. A piece of tube alittle larger than the column, welded three nuts to the tube around the outside after drilling holes, then put a bolt thru the nut to lock the column in place inside the tube. Cut the tube at the appropriate angle- 20degrees in my case- and welded it to a plate that i made using the original rubber dust shield as a template and cutting the center with a hole saw the same size as the tube. Bolt that to the firewall, install column.
They sell the joints that fit the column and you can weld/bolt in place your shaft from there. From what i understand, Ididit and Flaming river both make columns based on GM column design, so be prepared to get a hub adapter for your wheel as well. Then you need to adapt the wiring.....i havent gotten that far yet.