340 coolant temperature

Need some help on what is happening on my 68 Barracuda with 340.

It runs good at idle and upto 2000rpm and temp shows 160 on dial and just below centre on original guage.

When above 2000 to 3000rpm then temp goes up to 190 and between centre to High on the gauge.

The car has alu radiator with two electric fans and funnel, fans come on as soon as ignition is on.

I have tried to 3300rpm and temp goes above 190, so I stopped.

Any advice on what to look for and check, the car came as it is and I have just started using it.