I'd sell it.
I get sentimental about cars, too, but in the end they're just appliances like a washer or a dryer.
If its already gonna need work, and it already will need a motor swap to have enough power, you're behind from the get go.
Your grampa would want you to be out enjoying life and the outdoors rather than under a truck in a garage, right?
I assume you have another vehicle?
Why not take money from the sale of this truck, and take a trip or make an upgrade, in his memory? Every time I think of putting a snorkel on my truck, I think of my dad and I swapping the blown motor out of my 4runner when I was in college. (the result of a water hole) Haha!
While my Dad is still firmly with us, snorkels still remind me of that whole experience, and how much he means to me.
I'm sure you'll make the right choice for you!
"For He so loved the world, that He sent His only son..."
1992 XJ:"Daddy's Jeep" - The "Please don't hit my Jeep again!" Edition.
2009 Ford Edge:"Penny"- "Mama's new ride, and our new trip car"