If you are using the factory head...which I am sure you are you'd want to put the 1.6 rockers on the exhaust side.....because the exhaust side is restrictive....

I would probably just buy a set of 1.5 and put them on because 1.6's usually are not a direct fit.....they cause the push rod to rub the passage where they go thru the head....always been my case....to fix you have to drill out the push rod holes and you don't want to do this with the heads on the vehical...