Dashswap pitfalls and worries and advice please

Best advice I can give is to just take your time. That's old plastic and if you are too aggresive you can end up breaking something. If something feels like it's not free check for a hidden screw

As for the ducting I think that was prob the most difficult part. THere are a couple screws in the drivers foot area that need to be removed.

I swapped in a '92 interior into my '89 Hatch and there are a few things to be aware of. The seatbelt height is different and I needed to drill some new holes higher up(or was it lower) to mount the seatbelt on the inside B pillar. The other issue I ran into is where my fuse panel was there wasn't a specific mounting point for me. I ended up modifying the lower part of the dash so it would clear and I could access it easily. Other than that it's a fairly bolt in procedure.

I guess I am confused but.. why would one swap out the dash from 88 to a 93?

The only real differences in fitment are the AC controls - the 90-93 mount differently than the 87-89 controls, so I would recommend using the 90-93 controls if you can. You will have to extend the yellow defroster damper vacuum hose a small bit since the control is moved to the right side from the left, but it all works. Or you can drill a couple of new holes and mount the old panel in the newer dash. It will be covered by the trim anyway.

Also the fuse box mounting is different. The 90-93 have the fuse box under the dash, not behind a removable panel like the 87-89. You can mount it under the dash (a bit of a PITA to get to the fuses unless you get the 90-93 metal frame that folds down) or you can cut out a hole in the 93 dash and mount it in there under the knee pad. Just omit the metal backing panel from the knee pad and it works fine.

Pics of mine - I should have cut the hole down a bit as it was cut up too high at first:

http://statefilingsoftware.com/pictures/fusebox1.jpg
http://statefilingsoftware.com/pictures/fusebox2.jpg
http://statefilingsoftware.com/pictures/fusebox3.jpg

Tokyo your dash bares a striking resemblance to mine at this time!