The low output and horrible input VSWR was caused by a bad power FET from my original kit.
I ordered a spare set from Digikey. As usual, shipping was more than the parts cost.
But still a bargain, FedEx ground service from Minnesota, $6.99.
The IRF510 Pb-free-until-I-fixed-that parts came in this morning, and I popped two new ones in.
Drive is 4W from a QCX Mini, 7.02 MHz
The amplifier easily makes 55+ watts out now with 18 volts power, from a Bosch tool rechargeable pack.
Harmonics down 54 dB or more.
Perfect.

73 Steve KZ1X

How low was your power and how did you measure the vswr input? 
--
regards,
Bryan, N0LUF

Out of curiosity I out my Daiwa meter inline between the QCX+ and the 50W amp with a dummy load attached to the output of the amp.
I measured 1.8:1. 
Is this expected, or acceptable? Seems kind of high. Should I be looking into it further? 
--
regards,
Bryan, N0LUF

I got a response from Hans regarding that and it sound like the input impedance is not intended to be perfect 50 Ohms and what you have sounds completely normal. 
Steve, how did you figure it was a damaged FET? I'm struggling with low output too, is there an easy way to test these? I suppose I could put an oscilloscope on input and output and make sure there's gain?