Swap my car

[Shamil]

Some ideas are jumping on my mind….And make me crazy….
What I own is a chevy custom deluxe 30, 2wd with L6 3.5L and manual transmission of 4 speeds the first one is the low gear

1. One of the ideas is to swap my truck to 5.0L with 5 speed Automatic transmission and 4x4, this will cast me a lot of money

2. The second one is to keep the L6 engine and install a bigger carburetor; mine now is Rochester monojet; and to swap to 5 speed automatic transmission with 4x4.

I really need help especially for the second idea can I do that…If so what do I need parts, I need a mechanical experience

P.S I drive my truck everyday, so bare in mind fuel consumption