The Quads are lovely and seeing them still brings back nostalgic memories
Kel 84 is a really good amp and well worth rebuilding. Look for easy to drive 8 ohm speakers as number one priority, even before sensitivity, as if the load is difficult the response will be lumpy or missing bass etc. It is amazing the difference speaker load can make to some amps.
Older speakers were often of higher and smoother impedance probably due to the designers coming from the valve era and being more conscious of the effects of the amp/speaker interface. There are some great modern speakers too of course.
Good idea about a plug or terminal block for the pcb wiring but not so easy to do as a retro fit in practice. I certainly agree it would be a good idea for any further pcb WD amps to incorporate on the pcb.
On my WAD amps with pcbs I made life a little easier by making a common earth point on the pcb with a tinned copper wire loop to which the earth wires could be more easily soldered to
