Welcome Patrick,
Just my personal thoughts, but even if it left the factory as an L30/M20, with the original drivetrain now missing, you can build it to suit your preferences. Trying to piece together period-correct drivetrain components, all dated in the right timeframe, can get very expensive - especially as you're outside the USA.
Anyway, whatever you decide, enjoy your Camaro and keep us updated on your progress!
Tim