So it's probably a 13-15k truck fixed. Are you gonna swap the motor or pay someone to do it? I figure you've probably got a 10k plus bill for an ls2 and the swap costs.
With a blown motor, people have to "trust" that the trans is good, the suspension is fine, brakes, etc. I think it'd be tough to sell it for more than 3k without a motor. Having a bad fender hurts that too.
I don't think you're going to make appreciably more by fixing it. But you open up your potential buyers a lot because most people don't want to buy a non running vehicle and hope for the best.
If you can do the work yourself and have the time, you can do a L92 block and heads and such and make more power for a lot less than the 10k estimate.
If not, I'd just list it as is for 3500 and see what you get. Maybe someone wants a project.