I am the Supra pro here. Regard whatever other users tell you as Farce and non-information.
Now, with that out of the way, you ready to proceed ? Good, here we go:
1) Electrical problems on Toyotas are nightmares.
2) It's more than likely dead (originally) because of a blown head gasket. IT's THAT common.
3) The swap isn't worth it. Not even slightly.
4) a Head Gasket job is 21 hours on the books. Expect longer.
5) As a daily driver, the Supra may not be what you're looking for. It's large, heavy and far more of a GT car.
6) I love these cars. I can make them sit up and beg. I can guarantee that you will hate it. I come from a Vette / Muscle car / Supra background into the world of Hondas. If you're coming from a Honda into a Supra you'll hate it.
7) blown fuse or shock ? If he mentioned "Shocks" at all, he's talking about TEMS shocks. You can't get them anymore. IF the car is equipped with TEMS then when replacing these shocks, it'll be disabled and deadswitched.
8) If they hooked up a charger and wound up "possibly blowing a fuse" the "Possibly" is "More likely" that they fried a harness. Run from that deal.
9) "Few Rust Spots" with the Supra is serious. The Supra is covered with plastic doodads and covers - the rust is under those. Rust is a cancer - by the time you see it, it's everywhere... particularly on 80s Toyotas.
10) The easiest swap you can do on this car is a carbbed V8. At this point, with a $500 Supra (Which I would buy) I would have another $5000 on hand for the necessary repairs to make it livable. Livable, not excellent or sport worthy.
87s are rare, but they are also the most common Supra ever made. If it's an 86.5 (Perforated seats) then RUN FROM THAT CAR.
3rd Gen Supras are a kind of crap shoot. You never know what you're gonna get. There are some worth looking out for (Black and Beige turbos, hardtop turbos, ASC Sunroof models, the 92 Teals, the Triple white 90s, etc) but most are junk. the 2nd gen is more rewarding, better running, and all around slightly faster / lighter.
And 3rd gens, for having such a large body, have 0 interior space.