Wow! That's pretty incredible.
If you are starting from a position of not having to buy that 4runner, you're already $4-7000 ahead (really, I can assure you that, aside from the rust, that would sell for a lot in Western states like Colorado). So, if you take your time, do a lot of preventative maintenance with OEM or better parts, it'll pay off and be a car you own for the next decade, or really until you want something else.
I think it's important to consider time elapsed in addition to mileage. Gaskets and other components made of things like rubber degrade over time, regardless of use. It's just material science, but driving it certainly speeds that process up. Even if you don't *think* something needs to be replaced, if you put it on your "get around to it" plan, you'll be much better off for it.
It looks like you have a great garage space, so consider tools, floor jack, and jackstands as part of that investment into this truck! I think I can say we're all pretty damn jealous!