Many parts you cannot find new, but there are a lot of guys buying Capris to part out. If you do the Facebook thing, there's a very active group there where you will have good luck on a parts request.
https://www.facebook.com/groups/210318449008872You could also ask here but we don't get the same kind of traffic. (But the info is much better! ha) Probably the best place to find headlight motors.
eBay is also decent at times.
Rockauto.com is a great place to buy mechanical parts, look for 1988/89 Mazda 323. Many but not all parts are interchangeable.
The gas tank for the Mazda 323 is a direct fit. I think the parking brake stuff can be found there too
Shifter bushings you can buy new, the Festiva Store sells a whole kit with new bolts if yours are shot. Otherwise you can buy them at NAPA, the part number is somewhere here on the forum if you search for it.
https://www.thefestivastore.com/