Speaker for 5w Bugera tube guitar amp

I aim to recycle my old blackstar combo as a speaker cab  which came with a 10 inch 16 ohm .speaker.  The Bugera is 4 ohm so I decided to replace the speaker with another 10 inch.  The problem is they don't seem to make many 10 inch speakers at 4 ohm and the only one I could find on sale is the Jenson 10R.  This is 4 ohm 25 watt.  Although I get the impedance science I'm not too sure about the wattage rating/ amp output question.  Would the 25 watt speaker fit the 5w tube out put?

My other option would be to go for an 8 ohm and live with the subsequent  loss of volume.