The 8.00 in the old numeric tire sizing system indicates the section width (not height) in inches at the widest point of the tire.
Here's a good link that explains the different sizing systems:
http://dunlop.buffnet.net/tt101_sizing.html
I don't have literature for '64, but wouldn't be surprised if a slightly larger 14" tire was also available. In '61 & '62, the standard tire on the 88 was an 8.00 x 14, but an 8.50 x 14 was standard on AC cars & optional otherwise.
My 61's & 62's all sport repro bias tires from Coker. I had radials on all of them for awhile & thought the ride was very hard. I had a lot of folks tell me to avoid the bias tires, but I finally opted to put them on my '61 Starfire to bring it to AACA standards. Prepared for the worst, I was astounded at the improvement in the ride. It was a dramatic, night & day change in the ride quality, so eventually I put the bias tires on all my big Oldsmobiles, with similar results. The cars look better too, as they sit a bit higher, & the tall tires tend to fill the wheel wells more than the radials did.
I realize I am in a small minority in favoring the bias tires, but I don't mind sacrificing a bit of handling in favor of that wonderful old big-car ride. I admit, if I wanted to take a Starfire on a slalom course, I'd want to mount a set of radials, but I don't anticipate doing any road rallies in the forseeable future!