Apparently everyone in the world knew that 2SC3281/2SA1302 are most likely fakes. Toshiba doesn't produce these as of the year 2000 and originals are nowhere to be found. Again, ESP has a beautiful post about debunking counterfeits: http://sound.whsites.net/fake/counterfeit-p2.htm
Following the advice of many good people on Internet, I went on and purchased MJL3281/MJL1302 by On Semiconductor, from a reliable source (RS). This morning, I've tested the circuit with the new transistors and it worked like charm! Next step, finding a 100W speaker and testing out power performance.