If the OP isn't just a whelp wanting to stir the pot, then he has gotten his answer and is long gone.
8 years old is not too old to produce a litter, but having a first litter at 8 is way too risky. The problem is, that she can and probably WILL get pregnant if she is given the opportunity.
It is then, that you have to decide whether to spay abort, or try to let her go through with it. And the chances of complications skyrocket after the age of 5 or 6 for first-time litters. A large-breed bitch is closing into geriatric at this point, and the chances that she will not have the required stamina to produce a litter, the chances are very good that it will be very small, meaning much larger puppies, labor may not start, my start and stop, and she may not be able to push the large pups out.
Possible C-section. Will the instincts of motherhood kick in as strongly in an older bitch? Maybe. If she did not have them naturally? Maybe. Will she bounce back from a c-section? Maybe -- lots of maybes.
What you have to really ask yourself is whether you have the stamina to raise a litter if the bitch rejects them or is lost in the process. If you are ok with that, well, no one here is going to condone what you are doing. Read up on the process and pay special attention to when to call in the vet and get your bitch help if she is having trouble.
Heidi Ho, Odie
Joy-Joy, Bear Cub, Hepsi-Pepsi
Cujo2, Karma Chameleon
Ramona the Pest, Kojak -- who loves you baby?
Tiny Tinnie, Susie's Uzzi, Kaiah -- The Baby Monster.