Stunch, I'm a little confused by your statement concerning the current measurements. Where, and how are you are getting these readings? The output stages should not be drawing the amount of current you mention. If they are, you are in the danger zone! Way too much current if that's correct, but I suspect it isn't. Your voltages across the 5 ohm resistors is fine, if you are measuring it correctly.
The current of 27ma (per pair) is correctly set by measuring .27 VDC, drop across each 5 ohm cathode resistor. If you are using the single EFB bias circuit, then the potentiometer is adjusted to obtain the reading giving the closest average to .27VDC on each 5 ohm resistor. If you have the separate (individual channel adjustment) EFB circuit, then each channel can be adjusted to .27VDC individually.
To do this, the meter is set on the DC voltage scale. If you do not have an "autoranging" meter, you probably need to use the lowest, or next to lowest VDC range. One lead is placed at each end of the 5ohm resistor. The red lead should be placed on the end of the resistor that's closest to the cathodes of the output tubes. Otherwise the meter will read a "minus" voltage. This is okay though. Just ignore the minus sign on the display.
Current can be measured directly by your meter. But the procedure is different. Current is measured by a voltage drop across a known value resistor. In the case above, the resistor is already in the circuit (5 ohms). If you wish to measure current draw in another part of the circuit, then you can use the current scale on your meter, which uses a resistor that's already built in the meter. The leads are applied differently, however. The black lead is attached to one side of the circuit, usually ground, and the other lead is placed on the area of the circuit to be measured. This sometimes involves temporarily "opening" the circuit, so that the current is drawn through the meter, rather than through another part of the circuit. It's trickier than measuring voltage, and runs the risk of blowing the meter fuse or internal measuring resistor, if the current draw is excessive.
You need to adjust the current of the output tubes, using the procedure, above, then let us know about the voltages of the new 7247 tubes. That was the original concern. The minor reduction in AC line voltage that you mention, should have only a very slight effect on the output tube bias, and probably on the 7247 plate, grid and cathode voltages.