After a long Sunday of soldering, I've managed to get pretty far! The board fits in the chassis and all the components are attached. Here's a picture of the speaker with lead attached:
As you can see, everything fits and it looks pretty neat, too. The push-back wire is pretty easy to work with, since instead of having to strip bits of insulation off, you can push the insulation back to uncover the wire. Also, it doesn't melt like plastic cover, so when it gets hot the insulation doesn't fall off.
I've installed a small mod, the negative feedback is switchable. The sound is supposed to be less distorted with negative feedback, so this should be a nice add-on to the design. The switch may be in an awkward position though, it's located between the pre- and power amp tubes, right next to the speaker out. Oh well.
Next up: installing the final two parts - the two 100 Ohm resistors on the tube heater lines. After that, it's testing all the connections, powering up with the current limiter attached, measuring the voltages, installing the tubes, and keeping my fingers crossed...