Just some FYI, and a word of advice.
In your recent description of the car, you mentioned the hood - try to see if there is a hood tach, or at least 3 holes from where there was a hood tach (1 large hole 1" diameter, and a small hole on either side for locating pins).
All 175 Yenko Deuce Novas had black standard interiors, rubber mat floor covering, and bench seats - no buckets, so no consoles/guages. Try to get a look at the speedo in the dash, console/guage Novas had a tach dash. If this car has a console/guage package, but no tach dash - then the console/guage was added which would be a good sign. If there is a tach dash, that could be added too, so check the underdash heater box, real console cars get a special box under there which is rarely swapped out when adding a console - if it has the non-console box, that's a good sign. Also, no Yenko Deuce Novas had any Yenko lettering on the seats. It may have been added later by an owner though.
The Yenko Deuce Novas had Hurst Competition Plus shifters installed at GM, the only Nova to come so equipped. This shifter is very unique, has a sharp bend towards the seat, and will be round stock - not flat stock. It could have been changed at some point, but try to get a look.
Yenko Deuce Novas came in both Orange (10 produced, 7 found) and Red (35 produced, 17 found). So, either color is possible, however red is more likely because there are more unfound red cars. (If you name the state where this chicken coop is, I will be able to eliminate or include orange as a possibility).
As for the possibility of a clone in '78, it is indeed possible. Yenko SportsCars sold the stripe kits for both '69 and '70 versions in their parts catalog, including all of the Yenko installed items like tachs, wheels, emblems, steering wheels, sport mirrors, hood scoops, etc... Not likely that somebody would clone one in the '70's, but possible.
The most important piece of information that you need to obtain, even before you or your friend make a drive, is to obtain the information from the trim tag. The trim tag information is more important than the vin number. I can tell you almost anything you will want to know from one # off of that trim tag. So, try to get the owner, friend, somebody, to get that info before you spend a lot of time attempting to acquire the car.
Best of luck! More than one Yenko Deuce Nova has been found wasting away!
http://www.yenko.net/features/2001/field.jpg
Marlin