LT1 Vs 5.7 Vortec?

[BlackedoutC10]

Looking to start building a motor for my 83 c10. I have two options available right now one a 1999 suburban with a 5.7 vortec and just today a friend told me he has an lt1 motor out of a 1995 z28 and may be interest in a little AK 47 swapping for it.

I don't know anything about building motors and nothing about swapping them. This is going to be a good learning experience for me and i'm not planning to rush it (The original 305 is still running fine). What would the pros and cons of these two motors be and is one a better/cheaper motor to work with then the other.

Down the road id like to be able to maybe turbo the truck and just have something fun to drive but reliable. Id also like the have the gas mileage above 16-17 mpgs.

Any tips or suggestions appreciated! Thanks