Below are a selection of colour options for Franklin's outfit. The colours are picked directly from fashion items of the period and matched somewhat accordingly.
Some of the options are more outlandish than others, pushing the concept of pairing unsettling colours to imply a perpetual sense of dread an unease. Others are more muted, more in line with the muted colours of 1970s Britain.
Reading from the top left to the bottom right, I'm quite fond of the second, fourth, sixth, eighth and tenth options (which doesn't narrow it down by much, but still).
Each of these options seem to lean more towards a muted colour scheme, although I feel as though I need to retain a sliver of the 1970s brightness to prevent the outfit from drifting into the 1940s.