Subaru Conversion Information Resource Navigation Bar - over 160 pages of info on Subaru powered VW’s! :
Note a large piece of the engine bay 'firewall' has been removed. Removing this much is not strictly necessary, but it doesn't do any harm either. At least a small piece will have to be remover to make room for the Subaru radiator pipes. Removing this piece would not help on a Syncro, as the petrol tank is right behind.