If you can find one an A590 will fit on the external connector backwards, it'll allow you to add 2MB RAM and includes a 20MB HD. If it's too noisy smooth down the sharp edges of the fan, this reduces it a bit.
If you want to upgrade the speed you can add a 68010 which makes it about 10% faster.
I had this arrangement back er, long time ago...
2.5MB RAM & a 20MB HD made all my friends jelaous - those were the days!
