Sounds like a good motor; like anything else it is "whatever the market will bear", always a little luck involved, ie. someone with cash happens to be looking for one when you are selling, etc.
I would call the respected Porsche salvage yards, (Parts Heaven, Oklahoma Foreign, etc.), ask them what they sell good SC motors for and adjust accordingly. If it has stock exhaust and original studs, I would think that $4000.00 would be doing well, but I haven't actually shopped for one. (My SC already has an engine). As for the "here's what a rebuild COULD cost" angle, that is not how it generally works out for used engines, but good luck anyways!
