Sorry for the delay, I'm on the road this week.
Finding a commercial amp in that frequency range and power level is one thing, something rated or capable of linear operation is near impossible. You could try a conventional class B/C amp and turn up the bias and see what happens. I looked at some of the TV fets, and they recommend somewhere around 1.5-2A per fet. With 50V of drain, that's about 200W of static dissipation! With a push pull circuit, I'd try between 0.5-1A of bias (1-2A total) and see what the intermod looks like. I'm not aware of any COTS amplifiers for this level, although a SD2942 pallet would be a good place to start. Not cheap, about $400 US, but I do know that particular fet is used in Digital FM band transmitters in class AB linear.
+-RH