Trust me on this, the regular TBI system is NOT
Vortec friendly. We replaced a 95 TBI 305 with a Marine Vortec long block, used a Vortec dual plane intake, and a Holley TBI adapter, (just like the Projection one), and it took bigger injectors, a custom burned chip (twice), and still only ran barely acceptable @ idle. Now out on the road, it ran GOOD, plenty of power, much better fuel mileage than the 305 ever got, but at idle, it would stall, or almost stall, randomly, and all too frequently. We put a Holley 600 carb on it and it ran GREAT, but the 4L60E trans didn't work, so I had to switch it back. It's possible that an adjustable regulator and more fuel pressure may have cured it, or at least made it better, but the owner, my old boss, traded it off when the trans went bad. Not saying you won't be able to make it work, but be prepared for some tuning issues.