If it's blowing heaps of black smoke could it be to rich??
Being an NA we don't have much room at all to move on fuel pump adjustment..
They will blow a little when under load but if your seeing black smoke when cruzing then it's possible to rich and thus causing extra heat in the engine..

Apart from that.
If you trust your secondary temp gauge at 70c then I'd say all good and don't stress about the factory gauge