Depends.
Each KT150 draws 400ma more heater current. Can the mains transformer handle it? If the winding is 12.6V (tubes in series) then maybe, but if the winding is 6.3V then you need 400ma per tube.
Is that amp cathode biased? If so, then the KT150 will draw down to 34 volts, and going to max idle current of about 140ma per tube. Can the mains transformer (designed for the KT88 with an idle Class A current of about 85ma) handle it? Probably not.
What about the output transformer? You need at least a 70 watt P-P xfmr to handle the KT150 at Class A. That nearly double the Muzishare's 45W OPT's
If the amp is fixed bias, then the KT150 will be throttled back and you will not get any extra power. You can use it with no problem. Can't say what it will sound like, I know from experience that running Class A at less than 70% dissipation takes the life out of the sound.
Going to a KT150 requires an amp designed for a KT150. May work, but no telling what it will sound like.