Antigravity batteries?

[Henryford]

Hey all, I'm doing a cafe build on an '81 cb650c. It needs a new battery anyway so I'm thinking of going with an antigravity - my question is, has anyone here had success/failure with them before, and what size/model did you get? I'm looking to save money where I can so I'd rather get an eight-cell or the like instead of a twelve-cell if possible. Thanks in advance!