So British engine in a German plane....not worth the effort IMHO

Stock or no value

Think you might be referring to the A6M3 of the SoCal wing of the CAF in Camarillo: Mitsubichi AM63 Zero

Some cool stuff there . . .

On many Sundays during the summer around here we're treated to four AT-6 Texans flying in formation and -- every once in a while -- a P-51.

Yes, the original DB V-12's were mounted inverted (heads down) to make room for the cannon in the prop spinner, I heard.

Yes, they were injected... a big advantage initially against the carb'd Hurricanes and Spits when going inverted. The Brits did a 'fix' for that which allowed inverted flight for short periods.

The Spanish versions had the Merlins mounted right-side-up.