You would get 8 times the drain current at DC no doubt. Now imagine you have managed to bias everything in class A. Then your current swing will be 8 times higher. 8 times current swing x same R --> ideally you should get 8 times the voltage swing. But you will be limited by your supply voltage. Typically, a PA is designed such that at the peak point, your voltage swing amplitude equals the supply voltage (I assume you have used an inductance between the drain and supply). So for the same resistance, you will not get 8 times the voltage swing. You will clip and will end up with power in higher harmonics.
So, you need to change your input matching network so that you see 8 times lower resistance.
But that is not the end of it. Now because your transistor is 8 times larger, your capacitance will increase as well. For optimum power matching, you need to change the value of the capacitance and inductance.
In short, the answer is NO. Resources pointed out by pancho_hideboo are really excellent and you should go through them.