No, with a stroked 4g15, it wont overheat...if not habis liao powerzone kenak sue by those 4g15s that got 'stroked' by them, if still worried, just put in a twincore radiator to improve cooling
difference between a stock 4g15 and a stock 4g13 is obvious, and with a 4g15, it would be a better platform to start modding, this is my opinion
since the choice is only between these 2 engines, u will have to mod the 4g13 quite a bit to just match the stock 4g15...so for others here, dont need to mention 'if modify kao kao 4g15 baru can match stock 4g92/93' because threadstarter is only contemplating on doing up these 2 engines
retrofit, mebbe u shud go find the same car with urs, but with a stock 4g15 inside...then this may help u in making ur decision
just fyi, changing to a larger flywheel does not make u go faster