your amp wont like it. perhaps run a 4ohm non inductive power resistor in series with load for 2 channels.
I would think you should be able to run 2 channels in parrallel with a .1ohm resistor in series before they connect together allowing you to use the full amp. I think that will work but am not positive. I assume the amp has a common ground for the - terminals.
I agree the amp will not like it.
Your info indicates that the Bose are 4ohm speakers and using A + B will give you 2 ohms when in parallel. However your amp my have a switch that offers A alone or B alone or A + B in series. If you can confirm this last option then the amp will be safe since you will be loading it with 8ohms which you said was it's rating. But speakers in series do not sound nice.
I wonder if the Lux is able to run two sets of speakers, each 8 ohms. If so it will be able to run one set at 4 ohms, provided the A/B switch parallels the speakers, unlike the Fisher SS units that series the units when both A and B are operated. You can check that rather easily with 4 speakers for a short time.
Your 405 runs the A and B sets in parallel when they are both selected. You can run one set of speakers only. Two and the Lux will spite you by expiring. Nice sounding receiver but it has been prone to poor solder connections and a factory error with some units where the bias was set too darn high. A little TLC may be in order.