i believe the gb housing is the same just that they are using different ratio 1.3 vs 1.6.
like bro pomen gtr mentioned,if the head is similar then getting the r3 performance part is a good step.
if your budget permit then i have seen on the net someone using mix and match part from the campro family and then put on bot.his basic is campro block,head is from cfe engine variant (dont ask me how he fit it),add turbo.or course its very complicatedand cost quite high.from his claim the car produces 160hp++ from 1600 displacement.
fyi,if you change the stroker to 1.6 then there are no way anyone can know the mod by just looking at the engine.
you are not just getting a bit more power but the main thing improve is the driveability. consider this as a sleeper mod.