Just buy new it's the best deal out there and it all GM"S best performance parts inside. and sell all the parts you have you will spend less and have more in the end
http://www.1800runsnew.com/newbase-details-NLM.html#502

Yea that is full price. machine work, gaskets, new cam, new lifters etc. I think its a good deal. I just dont know much about 502's, I usually own outboards and this is a big step for me.

The Dart block is a great block. Go with it. May as well upgrade the horse power at the same time. Take advanage of the Dart block.