The next time you thinkabout it, look at what's in the fuel for a model airplane engine. If memory serves correct, there is nitro in it already which is why the model engines are so powerful.
The nice part about using the crankcase to pressurize the induction in a vavleless 2 stroke is that you have to move the piston and the air underneath it ANYWAY (think about it for a minute). Besides twice the power strokes, this is another reason why the 2 stroke makes more specific power than the 4 stroke - there is less pumping work loss.
You can easily make a boosted 2 sroke for inspiration - look into the workings of a 4:71 thru 8:71 Detroit diesel engine as they do exactly what you're proposing - compression ignition only (glow plug to start) with diesel fuel instead of nitro/methane.
It would be harder to make a sump drier than that of a model plane/car engine as it is pretty "dry" as the fuel not only cools and powers the engine but also lubes it.
A roots type blower takes LOTS of power to run. A turbo recovers wasted power. I don't think roots would be the way to go in a model. As your question is posed, it is impossible to answer. Suffice it to say, however, the boost would ultmately depend on blower sizing and pulley/drive ratio.
Then again, I"m an engineer and engineer's merely solve problems and do not necessarily come up with inordinately creative ways to do stuff. I believe that it was an engineer who proved that neither a bumble bee nor a humming bird could fly.... Another said that it would not be possible for a dragster to exceed 124mph or something ridiculous like that.
Yet, N/A pro stocks are running faster than the fuelers did in the 60's and fuelers are runnig 300 and change with gear and 90% nitro rules. All it takes is money and time and a group of engineers to design the hardware needed to go that fast - hardly DIY stuff done on cut-n-try basis....