Thanks, chrissev. I need to start looking at the for sale posts more often. The recent post on the SAE paper (which I read) was very enlightening. Turns out that the TD engine is different from the NA in many ways. I was not aware that the TD engine also has different/improved crank, main caps, valves, and swirl chambers. Is it folly to try to build a TD from an NA without these improvements? I'm particularly concerned about the valves and swirl chambers, so that would mean getting a real turbo head. I didn't realize that there was a difference between the turbo and NA mechanical heads.
Another option (and what I'm wanting to do if I can find one) is to install a 1.9 head. These apparently give better air flow than the 1.6 turbo heads so they interest me a lot (it would mean I can pump more air into the cylinders, and pump it faster) and they also can be used with a metal head gasket which can hold more boost. Add an intercooler and a ram air set up.....I am planning a summer project right now.....