As the output circuit is coupled to the load with the T2 transformer, you can simply connect one of load terminals to ground. If your load does not allow you to do it, you must use 200 Ohm, 50W resistor (not wire-wound due to the high frequency) instead as a "dummy load".
Then you can connect an oscilloscope probe (rated to >100 V p-p) and measure the output voltage across the load.
To measure the current, you can add a 1-Ohm resistor in series with the load, again best to the grounded point. Again use an oscilloscope to measure the voltage across this 1-Ohm resistor to find the current.