MG Car Repair: converting 2 mg batteries to one?, many cars, mgb

Question
How much work is it to install replace the two batteries in my 69 MGB with one?  Is it possible?
Thank you so much for your previous reply - it worked fine. (starting by compression).

Answer
Hi Carol,
Yes it is a common modification. I have seen many different versions. The easiest probably is to just modify the back of one of the boxes so a 12v will fit. Other options are to run the power cable into the trunk and put the battery in the trunk like many cars have done.
Howard