Well, I like to be careful when I'm advising other people. Especially since I haven't actually built a turbo conversion. But I am in the process of building one, and I've read a lot of material online and in books so I suppose I can go a little further.
Intercoolers are really important to turbo systems. Low heat in the intake means greater charge density; same idea as a cold air intake but on a bigger scale. I would be you can make the same power with 4 or 5 lbs intercooled than 6 or 7 lbs non-intercooled.
Most car intercoolers are limited because of size constrains and the need to limit intake volume to reduce lag. You don't have either limit really. You could plumb in a fairly big air water intercooler and get good results without worrying about lag.
Now, the intercooling will not work with a draw through system (carb feeding into turbo). You know how starting and driving is hard when the intake and engine is cold? That's because the fuel vapor condenses on the intake walls and cylinder walls and anything cold as it goes though. Now imagine how much will condense inside an intercooler. Add all that tubing and the fact that it won't be all down hill to the engine and you get puddles of fuel in the intake tract with no where to go. A very dangerous intake setup.
I would do it blow-through if I was going to do it. Big intercooler, feeding up to a enclosed box for the carb. The box wouldn't be too difficult because you've only got 4 or 5 lbs. Blow off valve before the carb so you can dump air and not worry about fuel.
I say a box because from what I've heard it's easier to enclose the carb often than to go for some kinda of sealed carb system. I'm not sure though, so this is worth looking into. The only bugger I see is the throttle shaft sealing, not sure about that.
Since you're not talking about a lot of boost either you should be able to setup the timing without any extra parts.
