Basically I made mounting brackets at the top of the dash in the center and left/right sides so I could bolt the dash in place. Then made some for the each lower corner to attach to the factory mount points. There's a center brace on the 69 dash so I welded a bracket to the firewall there for it to connect to. After that you need to modify the section that goes around the steering column, removing the center section of the hump that would normally go over the steering column and then small chunks of the factory brackets/steering column mount. The factory bolts for the steering column need to be removed and replaced with something just a bit longer and then you need about 5/16 worth of spacers to get things to line up right. I decided it was best if the location of the steering column mounting point didn't change up/down and then just worked around that.
I don't know if the factory AC/heater will work with this because I just replaced mine with a mini heater from vintage air. I'm guessing its not worth the trouble because that whole mess of stock stuff is insane. Just get a vintage air kit if needed. I Didn't want AC as I won't have room for extra junk in the engine bay with twins and piping ect. There seems to be plenty of room for gauges using either the original 69 gauge panel or an aftermarket.
It seems like the late model headlight switch won't be an issue and the wiper controls are on the turn signal lever, so just block out that section of the 69 dash.
The 82 factory VIN tag is still visible under the windshield but you need to fill in the section on the 69 dash because there's a hole there for the factory tag. I cut a patch and welded it in.
The 82 pillar moldings aren't gunna work though with out some modification. I may just hit up an interior guy for that but not too concerned with it at this point.
The width and size of the dash seems just about perfect. I'm almost wondering if a 69 console is a nice fit as well, might check that out too.