Damage to the HT spark system depends on how long you turned it over for and if a spark was ok when you started that proceedure. I've seen both 'buggered up' and 'got away with it' for the same time cranking.
Good - Fast - Cheap: Pick any two.
E23 735i; E32 735iL (X 2 - 1 Alpine White and 1 Glacier Blue); E34 535i; E38 735iL; R50 Cooper; R55 Cooper Clubman.
E21 318i; E30 318i; E32 735iL; E34 535i; E38 730iL; E53 4.4i