LS5 long block value?

[Andy]

This is the only forum I thought this question would fit, but if it needs to be moved some place else, then that is alright. My uncle has a complete LS5 longblock from a Chevelle. I am not sure what year LS5 it is but he is fairly certain it is from a 1970 model. It has been sitting on a stand for years and needs to be rebuilt. What would a motor like this be worth? The casting number on the back of the block is 3963512, and it has two bolt mains. It was an engine from a manual trans car I believe. It still had the flywheel on it. I will have to ask what the numbers are on the front pad, but I know that it had a C on the front pad, but I can not remember what the other letters/numbers where. The attached photo is the only picture I have of the complete motor.