umm crossover for me has allways been a particular sort of sound.
Bob Relf's 'Girl, You're My Kind Of Wonderful', T.S.U. Toronados - Only Inside', are what I consider crossover, but then what would you call stuff like Bobby Womack - 'How Could You Break My Heart', Ed Summers - 'I Can Tell'.
Just giving these examples because a couple are obviously 60's records and Ed Summers is an 80's record.
On a different note here's a bit of Bootsy Collins with his brother Phelps as the House Guests....I think all would agree pretty damned funky.
HOUSE GUESTS - MY MIND SET ME FREE PART 1 - HOUSE GUESTS -