Turbo on a 305 or 350?

As Corky said, there's a lot more to turbocharging an engine than just slapping one on. A good blow thru carb and boost referenced fuel pressure regulator will set you back some, as well as all of the fab work. It's not like anyone offers a "kit" to stick a turbo on a 2nd gen. Make a mistake, push too much boost or lean it out, and then watch the devastation.

 

I'd say that you're eventually going to build your engine (or a larger one) to a more turbo friendly setup, correct? Buy the size turbo that will fulfill your needs when you are done so that you won't have to go and repurchase anything.

As far as brands and sizing goes, I couldn't tell you. I've been out of the turbo game for a long time. Last time I messed with them was 15 years ago when I had my Grand National. Things have changed since then and the newer turbos are more efficient than they used to be.

 

A turbo set up (or supercharger) isn't cheap.
Supercharger gives you immeadiate power from idle on up and no turbo lag.

Turbos make the ultimate HP with intercoolers etc.
A blower can be simple and intercooled too.
Intercoolers aren't cheap either.
Power difference of a SC and a TC at low boost levels is small.

 

I think you will need more