Figure a good chunk of change say, 8K for a replacement, period correct engine if it can be found (just an estimate!) Then you get into the Boss351 specific items which are really hard to find. Also, check real close on the condition of the rear shock upper mounting area, these were often ripped out. They're a beautiful car and if you have a lead on one I'd love to hear about it! I can take 10 years to accumulate all the parts /forums/images/icons/smile.gif
Bottom line, there's not a lot of premium on the VIN alone because the cost items are all mechanical.
Just my opinion,
D