azsr20det

So i have a 91 SR redtop swapped hatch thats been sitting in a storage unit for years, well I finally towed it home and want to bring it back to life. It ran great before but its been sitting without being started for probably around 5-6 years. OBV it needs a new battery but I figured id start by flushing out all the fluids so im wondering what brands of fluid the experts here recommend?

Like I mentioned prior its a 91 S13 hatch with a SR20DET redtop and its got a t28 s15 turbo on it.

basically im wondering what brake fluid, coolant, oil, and powersteering fluid I should get and how much im going to need to completely replace the fluids as whats in there is super old and probably nasty af at this point.

Also I remember the fuel gauge not showing how much fuel is actually in the tank, I know the previous owner upgraded the pump to a walboro, but im fairly certain the gauge isnt reading because the little floater that attaches to the arm in the tank came off so the arm does not move up and down so the car doesnt know how much fuel is in the tank. Was wondering if there is any company that makes an aftermarket replacment for it or if anyone knows what to search in order to find the part. Ive tried 240 fuel level sensor, 240 fuel tank floater, etc but no luck. part of me kind of wants to replace the whole assembly but not sure where to go about getting it. so any help would be appreciated.

I had bought the car with a freshly rebuilt sr back in like 2010 and the inside and outside of the car looked like straight up crap so I spent countless hours and dollars bringing the visuals of the car up to par with the motor, repainted it inside and out (after scraping out all the sound deadening), fixed up the inside, (the dash was cracked to hell, completely redid the dash, shifter bezel, gauge bezel, and glove box door in custom carbon fiber, its beautiful) replaced the seats, shift knob, ,shift boot, did a quick release steering setup with nardi wheel, the list goes on and on

oh
Also i was wondering if anyone knew where to get a plug for the massive hole in the trunk near the spare tire well? the back of the car is gutted and has no trim panels past the backseat area

any help would be appreciated