There are several GM fuel injection systems, TBI or throttle body injection being the most common and likely the easiest. Converting to TBI would be alot less hassle than a TPI, There aren`t as many wires to worry about or system tuning. TBI was installed on millions of GM vehicles, it`s said to be the worst of injection, but it`s still worlds better than any carb will ever be.
My 92 chevy pickup with 270,000 miles has TBI and it still ran good up until the recent tear down. TBI will give a stocker 350 more low end power, while it`s not great on top end, if your not looking for a hot rod, TBI is the way to go. TPI isn`t much better on top end, but it has explosive low end response, tuned port injection is more sensitive, but also more costly and complicated. You can likely find a complete TBI system on ebay for your small block chevy at a good price.