I've run a CS MKII in my A3000D (no INT2 mod) without encountering any probs. It was more stable than in my 4000D when running alongside a deneb USB card. At the moment my A3000D is fitted out with an A3640 V3.1 board. The only issue with this board is the well documented issue with the capacitors being fitted the wrong way round, which can cause them to leak. Also there is no ram on the board, which really throttles the speed.
For the 3000D I'd suggest considering the CS MKII only be aware of the confines of the A3000D's case, which will limit you to fitting a half height heat sink, unless you want to cut out the tray for the floppy drives to allow you to fit a full heat sink with a fan (needed if you want to seriously over clock the card).
Weed.
