i got a very good idea in what ur interested, probobly the best out of this site. my dad (Best) and i have a blaster with the original motor, a blaster with a dt200 motor, and a blaster with a ktm sx250 motor. My advice to you USE THE AIRCOOLED MOTOR. dads ktmblaster was built by him and it took about 2-4 months start to finish and there is alot involved in swapping. HUGE hp and tq but loads of vibrations. most of these swaps are never completed and steer people away.
the dt200 blaster if u can find one BUY IT there very neat in a blaster and VERY peppy. compared to the aircooled blaster motor the dt sounds like a motocross bike motor, revs sound amazing and pulls hard. the engines are not the exact same theres big differences in the combustion area of the engines with causes the dtmotor to make double the power of the blaster. BUTTT the blaster motor can easily be built the exact same specs to make the same power.
after knowing all this and experimenting with them i recommend rebuilding that blaster engine they are awsome, easy to mod and cheap to rebuild. there lightweight with no watercooling and sound amazing with a good pipe behind them. hope this helps