The model change from 89 to 90 introduced all new sheet metal up front. To add some salt to the wound, I'm told (and actually seen for myself in the illustrated parts breakdown)that it all changed again, slightly, in 91. This makes the 90 a rare bird.

It might be that an entire front clip from a 91-up 740 or 940 might work, but I don't know if anyone on the BB has proven it.

For what it's worth, I feel you pain. I've got a 90 that I'd like to find another hood for. (Large niece sat down hard on it.) There ain't much out there.