A radiator is pretty much a radiator, so I'd fit the correct part. You need the right one with the built-in oil cooler for a 19J.
You could fit a later 200/300tdi unit with the intercooler, which may help to reduce the heat stress a 19J tends to suffer from. If you did this without tinkering with the fuelling or turbo pressure (which will be measured pre-intercooler) then the actual air mass into the engine will be the same.