Speaker wire should be a W and a W/B thru dash harness to body harness to left rear just slightly shorter than the antenna wiring. In the 240's I've seen (taken apart) they are in the 4-pin at the back of the radio with the power wire, but I don't remember if I've seen that connector on a Series One specifically.
(and I've always wondered why they label the blower motor "cooler"... I mean, ya, it can be used as a vent but I would hazard that mostly it's used as a heater... Just sayin')
Oh, Very nice schematic! except for the speaker wire... and it needs a speaker icon... but only one...