You've done everyhing right. I agree with Micron and Wrenchbender: it might be your starter and/or your battery. A regular 6v battery might not have a lot of cranking power after sitting in a store for a long time. Optima 6v batteries have much more Cold Cranking Amps than other 6v batteries. If you were near me, I would offer to test your starting set-up with an Optima Red Cap battery.
If it is not the starter or the battery (and both your cables are indeed 00 cables), your bearings might be too tight. There are ways of testing this but it is beyond my experiences/ability.
