Want to see pics: 67/68 Chevy with a 5.3

[The Big Green]

I have a 67 Chevy swb and I would love to sell my engine and install a newer engine with overdrive and a computer, my poor trucks needs an upgrade. How hard is this swap and what are you guys getting as far a gas mileage? Is it well worth $3000 to $4000 for the newer engine and tranny swap....nevermind I think I may know. I like my 350 and the compression and cam and HP, but its just not very practical because it gets 10mpg and I have to run atleast 93 and theres only a few places with that around here. I would like have pics of what this swap looks like, and what I'd be getting myself into.

69 thru 72 would be ok, but 67/68 is just my year.