ATM 3" spherical OK for scope?

["James Taylor" <u2pilot@satx.rr.com>]

I saw 3" spherical, coated mirrors at Surplus Shed today for next to
nothing.  They are f/10 mirrors.  Would a couple 3" spherical mirrors
(assuming it's a good sphere) be OK to use to make a small binocular scope
without turning them into parabolas?  Or how about a small Newt to use as a
large finder or guide scope?

I thought a small binocular scope might be fun to tinker with and would it
be worth my time buying a couple of those mirrors and putting them in the
closet until I can get around to it?  They have them for $4 in uncoated full
thickness and up to $13 for coated .34" thick.

James Taylor