Welcome Simon
...... personally I consider 1500or 1300 Spitfires in pretty-much the same way, mostly a question of whether you prefer the earlier or later styling.
I’v driven 1300MkIV’s, 1500’s, MkIV’s with a 1500 engine and 1500 with a 1300 engine....... the one mechanical item I would always look for is overdrive!
then it is simply down to condition - bodywork is always a bigger draw on your wallet than the oily bits which really are nice and easy to work with.
all the best with your search.... the more you look at the clearer it will be when you are standing in front of the right one
....... Andy