Thinkin' about a 6.2

[1968CHEVYC10]

Here's my current setup, I've got a 68 c10 with a '75 350 and a 3spd on the column. The 350 is pretty worn out, burns oil and could probably use an bottom end rebuild, new pistons and what not. The transmission I'm thinking is on it's last leg, and the clutch doesn't have much left.

Now here's what I want, 6.2 diesel with a banks turbo kit (turbo not totally necessary but it'd be nice) tied to a nv4500. Doesn't really have to be this exact transmission but an overdrive manual is what I want.

So here's what I'm thinking, my current drivetrain is pretty worn out, and my mileage really stinks right now, probably about 8-10, The carb does need rebuilding which I plan on doing but still wont be doing much better'n 12mpg or so. So I'm thinking in the next 6 months I'll be needing to do some major drivetrain overhaul. So instead of rebuilding everything why not spend a little extra and get way better mileage and at least equal power with a 6.2 diesel?

Few questions about the 6.2, are these things mechanically injected? Basically what I'm asking is will I have a mess of a wiring harness to mess with? what other extra costs are there besides the motor? radiators?, exhaust? (currently I have duals with glasspacks), I'm thinking I would keep this, and alter it as necessary to fit? Are there any extra emissions stuff I would need? like cats? I live in TX.

As far as the tranny goes what all will bolt up to the 6.2? If I did decide to keep my 3 spd would it bolt up? and would I be able to keep my mechanical clutch?

Appreciate the help, I'd be really lost without this forum!

oh and here's a pic of the truck, nothin special but she's all mine.