Junkers factory was in Dessau, Saxony-Anhalt which was in the Russian zone, so re-opening it seems rather
unlikely.
Focke-Wulf was in Bremen, but continued bombing led to new facilities in
eastern Germany and Poland. See above for why that's a geo-political problem, also F-W used forced, slave and POW labour, so I
don't suppose those were the workers Darryl had in mind.
Ju 52 production did continue post-war in France and Spain.
R-2600 or R-2800 would be overkill on the Tante Ju. R-1820 or R-1830 more likely, and a pair of either
would suffice to replace the three BMW 132s. Swedish Ju 52 used P&W Wasp S3H1G(R-1340).