I have an 87 n/a fc. I was wondering how I can go about installing a deck as mine came without a radio?
Second my car cane with a short shifter installed which I hate, what do i need to return it back to stock.

 

You need a stock shift lever.

 

Any idea if it's a pain in the *** job? Also any chance this part might be available online?

 

Peruse the classifieds contained in this site.

 

pop the shifter surround and boot off with a flat edge screw driver.(if you can get the **** off it is easier to work with)
see 3 10mm bolt heads in a triangular pattern surrounding the shifter..take them out.
pull shifter straight up,while leaning it towards the driver's side.
There will be a collar inside the trans IF IT WAS a true short shifter.(it will be under the lower bushing).
Take that out.
put the bushing back into the trans.
jimmy the shifter back into the trans.past the retaining spring.it should settle in.
The shifter assembly should already have the top bushing on it.
you may want to just touch the top edges with sealant
put in 3 10mm bolts that are of suitable length to attach shifter assembly to the trans.
Done.

Stereo?...you never specified stock or aftermarket.
If aftermarket then it entails catching power to the deck,from the battery,antenna wires,(power antenna option?...need that info too)..extra amp?...say it or lose it....speaker placement..who's yer daddy...

 

Most double-DIN will work, or you can use a single-DIN with a spacer. Just keep in mind that these cars have weak alternators, so you will need an upgrade if you want a really loud system, but otherwise a regular stereo will work fine. If your car has the OEM antenna then you will need a 12v relay because the antenna works backwards, while an aftermarket antenna will work without a relay. If you don't know what you are doing then just have a stereo shop install it. If you want to try it yourself, see the wiring diagram at Foxed.ca - Mazda RX-7 Manuals

While you are at it, I recommend upgrading to the 89-92 stereo surround and heater vents. The 86-88 parts are too brittle and crack after a few years. The 89-92 parts are more rubberized and last a long time. The vents need to match the stereo surround.
https://www.mazdatrix.com/in-stere.htm

Just trade somebody. Even better, trade for an OEM shifter + $20 since the short shifter is worth a lot more money. See here for instructions:
https://www.mazdatrix.com/faq/ssinstal.htm