There's a few factors in buying a battery besides amps. A off-brand battery may not have the reserve that a better battery will. Here's some information to read about battery selection in the first link. The second link has the BCI size guide.
If the battery is still mounted in the front of the car, most name brands should have a large battery that will work. Some chain auto stores sell a battery based on their look-up guide. It's usually much smaller than the tray. Look for a battery first by physical size (BCI number) and then by CCA and the other information. I run a small block in my 72. The tray holds a BCI size 34. It's a 875 CCA battery by a known company. Something like that should turn your engine. Most batteries sold today have both top and side terminals. http://www.auburnextremeracing.com/info/battery_tech/ http://www.rtpnet.org/~teaa/bcigroup.html
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