[Jonboy]

I say do what you want with it. Lower it as much as you want. My '74 is lowered 6/8, and it was Scoti's daily driver for 8-9 years before I was able to talk him out of it. It also towed trailers regularly, and was his work truck. I swapped in a TBI 350 and 700R4 to (hopefully) get a little mileage out of it and stop a few leaks. I plan on using it as a driver soon as well, once the A/C is finished.

If you modify the truck to your needs, then who cares what it is worth to someone else? At any rate, it is a lot cheaper than a payment on a new truck.