Huh? So they converted a post-‘95 vehicle and engine to TBI, the year stated here is wrong, the friend is mistaken (confusing TBI and CSFI/MPFI), or it’s A TBI long or short block with Vortec-era engine management stuff.
Assuming it’s just a newer “Vortec 5700,” the improvements are a serpentine accessory drive, much better heads (assuming they’re not cracked, valve seals/guides shot and also the springs have a lift duration ceiling of .450 so if you want a cam that gives you more, you need upgraded springs), the cam is a better spec’d roller rather than hydraulic flat tappet, and the mechanical fuel pump provisions are general gone where it would be hit or miss on ‘87-‘95. With a Vortec TBI intake, you could probably run this engine without modding anything using your current engine management setup. Now if you wanted to use the OBDII stuff, you’d have to have the PCM, harness, sensors, etc.