But with the lightning longblock you'll be getting a set of GT40 heads for $25.00. The accessories from the truck might be worth the price of a set of GT40 iron heads if you have a market for them. Probably not though.
The warranty? It might be worth it too. The F150 could be a roller camshaft, with lifters, dogbone, etc. The cam could have a small value depending on your market. Lifters you could possibly reuse.
I'd probably weigh the value of the heads versus the warranty. What kind of shape is the lightning motor in? I assume it doesn't have the intake too? If it has even the lower I would say this makes it a no brainer.