351C where to start?

[giantpune]

There's not a whole lot to decode on that vin. Its only a partial. I think you already got the year-1973 and the plant was Atlanta. The rest is the sequential car number it came from. There were a handful of cars that came with a 351C, made in Atlanta in 1973. That could possibly be a ranchero or maybe a gran torino?

Nothing about that suggests that the block is not worth the effort. You may be dealing with a rebuild motor, or somebody could have pulled a complete motor out of a different car to plop in.

 

[Stanglover]

I'm not sure about the engine block casting letter "A".
If that motor is otherwise good, it probably should be a 4 bolt main, not that the extra bolts actually do much, so could well be worth rebuilding to whatever spec you want, keep it stockish or stroke it.
I'm definitely not the engine guy around here, so I'm sure others will chime in to help out.
One thing is for sure, you don't have the original motor in there.