With Kickstart 2.05, you should not use a Workbench of the 3.x variant as this can cause erratic behaviour. 2.0 and 2.1 should work fine, though.
If you want to use Workbench 3.x (both Kickstart & Workbench 3.1 have some nice bugfixes & speedups compared to 3.0), you should put in a Kickstart 3.1 ROM chip.
