There’s good info in this previous thread on the topic:
Can anyone recommend where I can purchase a new battery for C3. I’ve got the battery with screw in type on side not terminals ? Also it looks too small to me. Plus it’s dead !
www.corvetteclub.org.uk
Basically if you you still have the original side-post terminals then a type 75-60 or 75-70 battery is suitable.
Or if your car has been converted to top terminals then a 096 type or similar size will fit.
Top terminals allow the use of quick release connectors so you can isolate the battery when the car is not in use.