Suspension and power steering

You can keep your column if you don't mind cutting the shaft off. Measure the diameter of the shaft, I think it's 3/4", might be 1".  Speedway Motors has a rag joint with a 3/4" x 30 spline (most GM power steering boxes) on one side and a 1" or 3/4" Double D (or DD) on the other. A "Double D" or "DD" shaft is of the stated diameter with two flats opposite each other ( a "Single D" or "D" would have one flat). Easy to grind the flats on the shaft.

I've done this before.I suggest cutting the shaft about 1/2" longer than you think it should be, assembling with steering wheel, measure gap between wheel and column, then trim shaft down to where you have about 1/8" gap between hack of wheel and column base. You might want to measure the gap before you take it all apart. A little more gap is better than not enough! The shaft may go in a little more as the rag joint "settles in" with use. You can still run the horn wire up through the shaft and rag joint, but will need  more slack, IIRC. Don't recall how I ran the horn wire!

Mine was converted, but I'm using a late 80s S-10 tilt steering column and an intermediate shaft from something from a salvage yard (another GM). Don't recall what, I just looked through a pick-n-pull for an appropriate length shaft, still had to shorten it a little. Some of the shafts are easy to shorten (try early 80s?), as they have a little leaf spring inside. Others aren't -- they use a nylon pin to hold them in place. You can break the pin and shorten the shaft though. It may come apart when you take one end loose though.  I don't see this as a safety issue unless you shorten one end too much. I mean if something happens bad enough to pull the shaft apart in a wreck or the steering box literally falls off you're not going to be worried about/able to steer anyway! Could be a nuisance when working on the car though.

I used a standard GM box from a late model Concord. I had an issue with the pitman rod end -- there was a change in the taper at some point, I think 65 or 66 uses the late model GM taper, earlier (my 63) uses a different taper. So I had to use an early model pitman arm. Don't recall the exact solution, but I think I used a 65 Classic w/power steering arm (I have a 63 Classic), first year of the GM box. It is possible to ream the end to the right size, might have to weld some. You can also get a grade 8 (hardened) washer and ream it to the base or small end (whichever needs changing.. might be both?) of the tie-rod end, then weld those in place. I did that at one point on steering arms I made for a rack and pinion conversion (lots of trouble, no real gain!). Worked great, but when I had some issues with the first arms I made I ordered predrilled tie rod end bungs from Speedway and welded those on.

I just drilled the sill for the new box and used the Concord spacer. The lowest/most forward factory bolt hole was used, the shaft aligned, then the other bolts holes drilled. I used fender washers on the outside to prevent crushing the sill. The new holes weren't to far away from the sleeved factory holes, which still support the sill from crushing. The uppermost hole was just above the sill, I used a pipe spacer on top of the sill for that one.