I'd say: Boston or Ki-67...
- Decent bombload Boston 2k x 3, Ki 800kgx3
- Good climb rate bomber
- Very high accuracy
- Good chances to escape especially around 15-20k, but also reasonably easy over 10-12K as well especially if some friendlies around.
It wouldn't take much more time than any other fighter (due to good climb) but it would allow to deliver bombs accurately - over more targets, and due to high speed of these bombers escape safely.
But if you really want only 1000lb of bombs - just take Pony.