My big bore 1200 engine was used in my 1000 sedan for years behind a stock/original radiator & even fully loaded & towing a boat, no problem, then for a couple of years in my 1200 ute with a stock/original radiator, no problem, then back into my 1000 sedan, again without problem.

I will be using a heavy duty 1000 radiator in front of my A13 & it only got that core because the original one was rotted & had to be replaced anyway. The extra few dollars for the heavy duty core was not a concern, so I got it because I could & because I want to fit aircon later on.

For A series applications on the street, the stock size is just fine.