Engine Swap?

[Tomaso]

Hi Guys,
I have a 1972 GMC Sierra Grande K2500 Camper Special. New original white over bronze paint looks great. Its got a leaky crate engine, but most of the truck is rust free original, or 98% restored.
I could use some advice on doing an engine swap, or at least a rebuild. I'm of two minds here. First choice would be an LS with a new trans. Second choice would be a "new" crate engine. Third choice would be to rebuild the crate I've got. Of course, cost is a factor overall.
Some of my buddies argue that the truck is so original (I'm only the second owner) that I should keep it as close to original as possible. However, I'm leaning towards at least a new intake and a computer driven fuel injection system to improve reliability and fuel milage. Any thoughts would be appreciated.
Tomaso