Hopping up Apple Hard Drives possible?

[kburtch@pts.mot.com (Kevin Burtch)]

I have a ProFile at home. (I think it's a 5 megger) I noticed it is an
ST-506 drive and that got me thinking: is it possible to swap in a bigger
drive? 40 to 100 meg MFM drives can be had dirt cheap now. Does anyone know
if and why there would be a limitation? Can the ROM (on the interface card)
support a different drive? If it needs to be changed, does anyone know what
might need changing? (I have an EPROM burner) 

The same questions apply to a Corvus hard drive and a Davong hard drive. I'm
not sure of the current size of them, but I have reason to believe they are
only about 5-10 meg. (they both had options for much larger drives too) The
Davong is a non-ProDOS drive, and the Corvus is a SOS drive. (Apple /// OS)

Anyone?

Thanks!
Kevin