ATM Tile tool on 8" blank

[Bill Prewitt <bprewitt@newreach.net>]

I picked up a pair of 8" full thickness Pyrex blanks from a guy who 
had started rough grinding the pair but soon quit. There is less than 
1/32" sagitta so far. I intend to make a pair of f6 mirrors matched
as closely as possible.

    <dumb questions follow>
Does it make sense to make a tile tool so I can use both blanks ?       
What I have found in the archives on tile tools seems to mostly be 
for bigger mirrors.

The Willman Bell catalog said their hex tile is intended for 10" or 
larger blanks. Would this be because of microripple or economics ?

Will I have problems grinding the convex blank ?
                    TIA,
                    Bill Prewitt