Believe it or not, SERA has allocated frequencies for crossband repeat use. There is only an allocation for the 70cm band.
You can find the full document here.
Channels for Fixed Stations ONLY, 12 Simplex Channels, for Fixed Cross Band Repeat
| 440.7375 | 440.7625 | 440.7750 | 440.7875 | 440.8125 | 440.8250 |
| 440.8375 | 440.8500 | 440.8625 | 440.8750 | 440.8875 | 440.9000 |
Channels for Mobile Stations ONLY, 12 Simplex Channels, for Mobile Cross Band Repeat
| 445.7375 | 445.7625 | 445.7750 | 445.7875 | 445.8125 | 445.8250 |
| 445.8375 | 445.8500 | 445.8625 | 445.8750 | 445.8875 | 445.9000 |