I bought the biggest freakin battery I could find at Advance Auto! (uh, biggest in CCA, not physical size) I want to say it is 800? 900? I dunno, I'd have to look - but I remember the prices got funky - they went up as the CCA's went up, but then dipped near the top of my selection choice to a bit cheaper.
CCA = Cold Cranking Amps.
I paid around $80-85 for it after the core charge. (old battery exchange)
'68 Firebird, 350-4, 2 spd auto, triple black, Dlx Interior
i bought the biggest one i could find, partially because i had ooold wiring and i didnt have the best of conductivity, i think it was 1000 CCA and 1100 CA(had to shop around quiote a bit). But my dad tells me stories of how he used to buy marine boat batteries and put them in his muscle cares(corvettes and trans ams). Sounds like overkill to me but he still thinks its the best way to go
I bought a Die Hard and picked the 5 yr warranty one...no matter which battery you buy, check the warranty time, usually that is just about the time they will last ....then buy a new...
fnfbird & OS, I was thinking of doing kind of a combination of what you were both mentioning. I want the Optima, but as my 67 is Blue was thinking of going with the Blue Top Marine Optima.
I haven't done a specific search for over all dimentions as of yet, just some quick price comparisons...
Go to a reputible retailer... like Sears etc. who would have a good cross reference and measure the over all dimentions... then go get your Optima based on the dimentions? Just a thought...