Another signalling situation

Partnership agreement check. This one was put up on a Swedish bulletin board by Jan Lagerman.

______AK85
______J
______AQJ8
______JT96
963
A9843
53
AK8

West/NS, auction:
1H - (X) - 4H - (4S) all pass

You lead the obvious high club and partner plays an inconclusive 5 of clubs, playing upside-down attitude, as declarer follows with the queen. What's next?

We can see 3 tricks for the defence (the other high club is cashing since partner would have played the 7 with 75432) and the setting trick must be a club ruff or the K of diamond (if partner has it). So, we cash the ace of H and awaits partner's signal. So far - so good.

The issue is how partner's signal should be interpreted. Either...
a) suit-preference -> low H = club ruff and high H = shift to D
b) attitude -> low H (encour.) = shift to D and high H (discour.) = club ruff

Playing standard attitude and suit-preference, these signals will be the same this time (high H disc = club ruff works out for both 'schools' regardless) but with upside-down attitude you better know how to handle this as it points in different directions.

Our preference/agreement is attitude and partner will know what to do.