what gen are we talkin about here, 2G's have a 420a (like neons) for the rs and gs (except gs spyder, 4g64) and the gst/gsx has the 4g63 every 2.0 1G is a 4g63.

timing belt is on the driver side for a 4g63 turbo or not

and if im understand you correctly, no you cannot put 4g63 parts on a 420a.