That should work, though we decided on G3 to use standard area checks to make it easier to identify platform-dependent code across mods. In the mods I'm converting, I just assign a variable declaration section up front for all the platform-dependent resources, with three subsections (one for Tutu, one for BGT and one for BG1) for example:
ACTION_IF FILE_EXISTS_IN_GAME ~FW0100.ARE~ THEN BEGIN //Tutu
SPRINT "Z1900" "FW1900"
END
ACTION_IF FILE_EXISTS_IN_GAME ~AR7200.ARE~ THEN BEGIN //BGT
SPRINT "Z1900" "AR####" //not sure what this is offhand, but I have a conversion list on G3 if you're interested
END
ACTION_IF FILE_EXISTS_IN_GAME ~AR0100.ARE~ THEN BEGIN //BG1
SPRINT "Z1900" "AR1900"
END
COPY_EXISTING ~%Z1900%~ ~override~
That saves having 3 separate sections of code otherwise (just 3 separate variable sections, which is a lot shorter in my TP2).