Probably not a lot. To regain correct rotation, you need to change the crank (wrong
oil grooves at the end seal) and cam (and lifters). Not sure, but probably the dist too (due to the drive gear). And it is most likely a center-oiler vs the more desireable side-oiler. I'd say top dollar would only be $1000, but I coudl be way off.....
hmmmm....a 390 crank might work. Might be worthwhile to do the conversion yourself and then try to sell it.