Switching to Manual Steering

I'm thinking about retiring so I have more time to finish working on this car. :)

I spent a good 20 minutes making sure the box was centered, connected the column to the adapter to the box, bolted the steering column back up, bolted the starter back up...ran out of time. I should only need another hour or two so it will take me 10.

So I'm worried that the adapter might be a tiny bit off. With everything bolted up from whence it came, I can't quite get the slot for the pins to be 100% clear on both the shaft from the box and the column at the same time...there's a little corner of the splined section still visible. Has anyone used one of these before? I don't think I can adjust the position of the column...If I could back the column out 2-3mm, I should be ok.

Is putting washers on at the firewall mounting plate a bad idea? That might do the trick.

thoughts welcome.