1969 Yellow Yellow Z28 RS project

[DW31S]

I know where a Yellow/Black vinyl top with Yellow Houndstooth Z/28 is available. It has a 302 in it now that is NOT the original engine, but the original IS included with the sale. It is a running, driving car that basically needs everything.
How many interiors like that were produced? Any idea? If someone really is interested in buying it, I know the owner pretty well. It is located in PA. I'm thinking somewhere around $30k as is would probably buy it.