You can't wring the full potential of the M42 at stock compression ratio's.
10:1 is too high. If you want to make power you need 8.5:1 and run the blower faster. Otherwise det city here ya come. The 200 to 240 range HP is realistic with caution. Much beyond that and your fighting the inevitable meltdown. Import tuners are like gambling addicts, They only talk about what they won never what they lost. (Broken engines, tranny's etc....) Whether you go DASC or KO the blowers are the same,(For practical discussion) Other than different intake manifolds and a few other detail items ultimate power is going to be pretty much the same AFTER you learn and tune it. If you do a little web surfing on the Magnesun and Eaton sites there are very good tables on Boost to HP and the actual results are pretty close.
You should also read
http://www.sdsefi.com/tech.html For a lot of good pretty straight info.
Just my opinion mind you....
Dave