As a conclusion on my research until now(talking to many people, books, etc) it seems that you can easily get over 150hp-180hp streetable with a CIS turbo system, a mild turbo cam and some head work.And that's a 2L vanagon engine not a 100hp porsche...
As I've calculated it should cost less that $1200 if you have a rebuilt engine already and can find the admission parts at reasonable prices. (and of course, if you have the skills)

good luck!

A 1914 T1 and a 2.0L TIV are probably about equal.