Wow! Welcome, and kudos to you for taking on this level of project...it will be extremely rewarding to see it coming back to life.
You might want to check out ClassicZCars.com, as well -- they have a very big restoration community there. As an example, check out this thread to see some really nice custom structural metal work: https://www.classiczcars.com/forums/topic/61483-240z-fabbing-new-front-rails/. There are a couple of good vendors for replacement body panels, or you can fabricate your own.
https://www.baddogparts.com/store/
https://kfvintagejdm.com/
https://www.facebook.com/DatsunRescue (Adam Sylvester is a genius at locating those impossible-to-find used parts for very reasonable prices).
If you're not hung up on this project being a "restoration" (vs resto-mod), that'll free up all kinds of options for you. Example: rather than replacing that half-dash with an expensive, hard-to-find original dash; build your own custom aluminum dash.
Looking forward to seeing this beauty come back to life. Cheers!