ideal dérailleur height for a Deore on non-round/oval Cranksets (e.g. a Biopace)?
The bottom of the front cage on your front derailleur should be about 2mm higher than the chain ring, when the derailleur has no cable tension. 

That is, when it is in the smallest front gear position.

On Bio-pace rings, that doesn't change. but it must be measured at the point when the chain ring comes closest to the derailleur cage. (The hardest part of your large ring.)

Some older derailleurs may have had different expectations. But not that I am aware of.