Alpha 13 takeoffs from a MotoAmerica racer are going to be your best bang for the buck. the 150 rear is a bit pinched for the stock 250 rim but I don't think that would be a big deal at your level.
The Alpha 13's are not really race tires even though they are used for the KTM cup races in the MotoAmerica series. They are basically a "Hypersport" street tire although the A-13 SP tires that are out now do have a little more edge grip. Everyone
If you run them without warmers set the front at 30psi and the rear at 28psi cold:
http://stores.racetireservice.com/AL...ninja-KTM-390/
Takeoffs look like about $150.00 shipped from a KTM racer :
https://www.ninjette.org/forums/show...1&postcount=16