¿small engine? 1980 blazer 6 cylinders 250

Hello, i am Guillermo Arias, from Peru. Somebody is offering  to me a 1980 chevrolet blazer with an engine 6 cylinders 250 ci (4.1 liter).

I want to know:
-¿is this engine big enough for off roading pourposes? i am not trying to do extreme off roading, just travel to the beach, mountains and the rainforest.
-¿how is the mileage for this engine? miles per gallon
-this truck uses 4 leaf springs for suspension. Is it better than coil springs? Pros / cons?

if is there anything useful i should know about this truck, please let me know.

Thanks

The engine size should be good enough as long as you have the tires for traction on hills and sand. And if the engine is in good condition, if it is weak then steep hills might slow you down a little, but this engine should be fine for what you are planning on...