'84 was the first year of the SVO. Yes, they were EFI, the 2.3 EFI Turbo actually debuted the year before that in the Thunderbird.
Stock turbo on it should be a .60/.48 T3. You can turn it up pretty good, the engine itself can take about anything you can throw at it (lots of guys run 20 psi on a stock bottom end) but you will want a good intercooler for anything that high!
A Turbo coupe intercooler is supposed to be an upgrade over the stocker and they can be had pretty cheap. It's not as good as a front mount though.