Getting the Gunk Off

Can anyone reccommend a commercially available de-greaser (or home brew) for getting 43 year old crud off plastic coated wires in the engine compartment
without runing the coating?
I don't mind doing it the hard way with a few squirts of plain old spray cleaner of some kind, but if there's something better out there, I'd love to know.
ZW / '63 Riviera

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