Which Battery ????

My 36 year old workshop manual says the battery should be 60ah.

On the Internet Tayna recommend a 52ah Numax at £58.99.

However, also on their website there is an identically sized 68ah (with correct terminal config) for £61.95.

Which is best for my 1969 1750 spider??

It will be good to fit a battery for the first time since about 1980 !!!!