In the bottom drivers side corner of the firewall, you have that block all the wires go into, to connect to the rest of the wires inside the car. Any way I can get a diagram of that block to know which wire went where on that block so I can do some custom wiring? thanks!

 

Unfortunately, there is no diagram that shows the fuse block and where it all goes wrapped up in one page.
There is a site with the diagrams copied from a service manual for an 86 which, will be the same wiring for your year (assuming its the 89 you are talking about)

http://92b4crs.tripod.com/86wiring/86wiringindex.html