This score was somehow off my radar (haven't seen the film, despite really enjoying Mickey Spillane in general), so out of curiosity I found the theme and it's really fun! I would've never guessed this was from a 1982 film as it sounds so very '70s, especially the strings and rhythm.
It's got a ridiculously dynamic main title too. I love this film, especially a lot of the sardonic humour. A pity it didn't catch on and get a sequel. I was glad La La Land brought out the CD but it is quite jazzy and perhaps avante-garde in some ways and maybe that hurt its wider appeal. For me though, it hits the spot