All you have to do to know where to start " in order" is to look long and hard at that pic that you just posted.
The car needs wheels and tires, and that vert back window replaced. Then it needs about ten dollars worth of quarters at the pressure wash, and wash off that peeling plastidip.
There is no sense in you spending one dime on "go fast" junk until you can actually get it to " go reliably". If it was so badly neglected, that it looks like this on the outside, you need to cover the safety issues first. Stock brakes are cheap, and as opposed to driving on some marginal pad thickness in anticipation of a 4wheel disc conversion, warranted.
Why you'd even take it around the block on a mini spare has me scratching my head. Put tires on the thing.
Shocks, struts, steering, brakes, bushings fluids, battery, charging, starter. Once all of that checks out, then start worrying about going faster.
Here is my 2 cents worth. This is what I did when I got my 89 gt.
i also planned on driving it although I did not plan on a restoration.
it had no modifications but needed the usual stuff to be drivable.
I went through the brakes, new pads, rotors, front brake hoses, shoes and drums. New shocks and struts. Fuel pump and filter, new clutch, flywheel and trans. I got some black pony wheels and new tires. I swapped the front seats for a pair that the springs would not stick me in the butt and then I was able to drive it without worrying about something going left when I turned right and I could stop when I needed to.
At this point you can plan your modifications.
I'm with @CarMichael Angelo - get it running and driving reliably and safely before you invest in anything. Once you have that accomplished, as I posted earlier, definitely go with subframe connectors at minimum. Trust me, you'll notice the difference! Once the body is strengthened and stiffened go for the go-fast goodies.