Vortec swap??

[454c10]

Whats it take to put a 6.0 vortec in a 79 gmc k20?

[BidEquation78]

engine, whatever trans or transmission adapter to your current transmission, new harness or modify the current one and delete all   accessory wires. For computer you need to either get the current one reflashed which is good, or you could use a Megasquirt setup and easily tune it yourself. Either computer setup you're looking at $400-$600 on the cheap side after wiring. Unless it has problems I'd let the stock engine alone because they tend to be extremely durable even with high miles

Check out this page    https://sites.google.com/site/sloppywiki/everything-ls/sloppyguidejunkyardturbols ..... probably the best site for anybody on a budget

[Captkaos]

You don't need to reflash the computer just remove the security out of it.  I don't see the need in buying another computer when the factory one is designed to last hundreds of thousands of mines.
Are you planning on just getting the motor or a trans also.  Keep in mind after 1988 on C/K (not our bod style) the transfer case drop in on the opposite side, so you will have to use a transfercase that you currently have bolted to a 4L60E or get one.  If you already have a good trans the LS will bolt to it, you just need to provide a TV cable.
You will need motor mounts also. 

[454c10]

I want to use my tanny and all but use the 6.0 vortec.