Look, a stock Contour that looks and works good with original equipment is what, $6-7K?
That's all you can expect to get for this without finding a buyer in advance.

Find a buyer in advance and work out a base price for the car that you will sell it at, then allow them the opportunity to dial in the extra goodies while you are in there. If you can't find a buyer,
Don't do anything extra other than put in a working ovalport conversion with a new clutch. Clutch is considered maintenance, everything else is gravy.
If you've got a set of headers available, those may help the sale, but just having a working 3L with a new clutch and good newer tires should be worth around 8K.

Former owner of '99 CSVT - Silver #222/2760 356/334 wHP/TQ at 10psi on pump gas! See My Mods '05 Volvo S40 Turbo 5 AWD with 6spd, Passion Red '06 Mazda5 Touring, 5spd,MTX, Black