well, personally i would give myself a few if not 6-10 inches of slack, enough to lay the cables outside the battery box, just incase(especially when you install and remove the battery you would have enough slack to get the cables out of the way, instead of them getting pinched along the sides and under the battery... kinda irritating sometimes;). Given that your car is a '68 it should be a top post battery, and hopefully you are going to stay with a top post(the side post is just a hassle to get the connectors on, with the little space between the battery and the box wall... a group size 24 battery should have been the original size for that car, and its 8.75 inches tall to the top of the post.... and that would be the taller of the batteries that would fit into the box... the other group size is a group 34, which is shorter in hieght, roughly 1 inch shorter...
here is a link to the megatron2 line of batteries at interstate batteries that includes deminsions and specifications for all the group sizes we carry. :) hth
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StingrayJim
NCM Lifetime Member #1936
Stingray's '76���������������������������� StingrayJr's '78���������������������������Lil Red '94


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