I've got both versions of the Spitfire and the XXII seems to work without the guns file. I tested it against an XXI U-boat and she reduced me to 23% before I shot her down - those cannon are evil!
I've also snagged the Tempest and Typhoon, neither of which I've got to work before. It looks like there may have been a common file in the Avro Rota which was causing CTDs on my install as once I'd remapped the Rota the other aircraft worked. Strange...
The Typhoon shocked me with it's rockets (fortunately they missed) and I've managed to do some initial testing on the mod which I want to create, so all's looking good.
Thanks for the help guys - much appreciated and I'm a fair way down the route I wanted to go!
ALAAAAAARRRMM!