Stuart wrote:

No, and although it all sounded very clever it failed [...]

A simpler way to think about it is to think of your genny as having a
current rating rather than a power rating. Since the power rating at
unity power factor is given as 650 watts, we can deduce that the current
rating is 650 watts divided by 230 volts, which is about 2.8 amps.

Most (or at least "many") appliance rating plates give a full-load
current rating. If this is 2.8 A or less, the genny should be able to
run the appliance OK (although it might struggle to start some things
with 'larger' motors).

--
Andy