Join Date: Jun 2014
Location: Rocket City USA
Since your Dad is the original owner, find every scrap of paperwork associated with the car. Dealer documents, sales brochures, and Ford manuals from 1966 are obvious. But also find every receipt from a service or oil change. Those trivial receipts often have the mileage and date on them, and a collection of them establish provenance. Make a scrapbook. Copies of old photos are very cool too. Mustang collectors geek-out over this type of stuff. More importantly, one-owner cars are now pretty rare. So you better be ready to back up such claims with solid evidence.
While this small effort won't add significant value to your car, it can make the car more attractive to Mustangs nerds. This is a very common I6 manual car that needs a total restoration. So don't expect Wayne Carini to come knocking on your door.
Granted, the market for old cars has gone way up since the 1990s when we still bought and sold them for $1K or less. But this inflation means an I6 coupe in "good" condition is worth about $6K to $7K without a cowl leak. If this car is in "fair" condition and has the cowl leak (very likely), runs and drives okay, has never been hit, does not have major rust, and has original paint, then my offer would be around $5K.
This is bit off topic but....to me these plain Sprint package cars are a good starting point for a V8 conversion. But the price has to be on the low side, the body needs to be pretty solid, and the all fiddly trim parts present to make the project fiscally manageable. After all, V8 conversions can be expensive projects. Not to mention that "while I'm here" scope-creep is nearly impossible to avoid. Since the entire I6 suspension and drivetrain must be tossed for safety reasons, you might as well disassemble the whole car. And while the car's apart, you might as well take 'er down to bare metal and fix any rust. And while you're doing such and such... and suddenly you've spent $30K restoring a T-code coupe.
Move along. Nothing to see here.