Can an Engine run on an engine test stand with a Holly sniper FI unit?

For break in with the EFI you should already have a good base tune map. If you don’t, I’d run it on a good known carb for the break in period. Once done and post break in check is done, slap that thing on there and setup a base tune on the run stand. It will have to be adjusted once in the car. Most of the EFI systems are self learning as the car is driving and/or you can create your own tunes. You’ll need the correct pumps on the run stand tank for fuel pressure, along with the correct wiring.