Unfortunately all SBC's look alike, and whoever stole it probably wont part it out, they'll probably change valve covers and intake; then repaint it and use it. Without opening the hood of every hotrod around with a SBC, I doubt you'll ever find it.
Had one SBC stolen many years ago, and never saw it again. But then my '55 gasser was also stolen in 1972, and never saw it again either. Just a shame that some of these dirtbags don't get caught in the act, and disappear!
Sun. morning someone tried to either steal the battery, or my '69 Suburban. Came out at 5:00 a.m. and hit the alarm disarm, and no beep. Looked at the truck and saw the hood open. Seems they carefully opened the hood and didn't set the alarm off, but when they pulled the positive battery cable it alarms as you remove power. I guess they got spooked and ran off at that point, because that's all they did. Neighbor saw someone running down the street at 3:30, so might have been the culprit.