Lol, didn’t catch you in time with my post edit:
Otherwise I’d at least resize to 768x326 instead of 720x326 to achieve the correct AR without needing to worry about PAR.
Pal 720x326 is still slightly anamorphic and stretches to 768x326. This is equal to a 2.35:1 AR. The equivalent at 720p is 1280x545. So nothing should get screwed up in the process 😃