Well, I bit the bullet and went for a 32MB partition. Apple HD Setup seemed to know exactly what the limit was for a Prodos partition - so I figure the 10MB reference in the docs is just a reflection of the times and the fact that 10MB was probably a big amount for an Apple II at the time.

Anyhoo, I've reinstalled 7.5.5 and as soon as I finished unstuffing some stuff, I'll install my IIe card and give it a blast.

Cheers all,