As pentode: 2.7 Watts; as triode, estimated 0.5 to 1.0 watts. Is this reasonable? A quarter the power by going triode? Look at 6L6: 5 or 10 watts pentode, 1.4 watts triode. 6L6GC can do a lot better than 1.4 watts triode because it is allowed a high plate+G2 voltage. But we should not run more than 250V-275V on irreplaceable globe '47s