Interesting thread.. some of my observations if you dont mind
1. The a3000 is the hardest amiga to take apart and work on/upgrade
2. The reason the a3000 is so small is because they were competing with the pc formfactors at that time and had to reduce the size drastically from the a2k.
3. Buster 11 is NOT necessary unless you are using high end zorro3 boards or certain boards.
4. Upgrading scsi chip will NOT increase speed and probably only helps with multiple devices. If you have a couple of units the default chip is fine. the a3000 scsi is very fast for an amiga as it has DMA and with a fast scsi drive is a sweet setup.
5. a3640 fits fine with a low profile heatsink (like the one that came on the amiga technologies a3640)
6. The Video Toaster 4000 fits perfectly in an a3000, i just saw a nice setup like this on us ebay:
http://www.ebay.com/itm/221163563442?ssPageName=STRK:MESELX:IT&_trksid=p3984.m1555.l2649