I would be very cautious about that. The Kustom 150 schemo I looked up has about +/-40V power supplies, the 2N3716 is rated for 60V and 80V BVceo. It wasn't known at the time of the Kustom 150s, but high BVceo lets you get larger safe operating area in bipolar output transistors. The old practice was to choose outputs with Vceo of equal to the whole power supply. Today, you can do much better at a good price. You'd be much better off with some of the newer devices, which run about $3.00-$4.00 each for a 160V to 200V device rated at 15-16A and 150W, with much extended safe operating area.
You might get lucky. But I never trust my luck in musical amps.