Battery relocation
I think you would be better off with the propper radiator, shroud, pulleys and fan.
I say that even though you've invested much effort in these modifications.
Another answer might be a more compact battery.
If you really want to go attempt this, based on our conversation, maybe a scheme like this would work if you want a master disconnect and a key disconnect for the heavy starter cable. Its got the relay wired as
@67Dart273 suggested in an another thread.
Or a slightly more robust layout, still assuming you'll be using an ammeter.
The igntition start wire is only partially drawn in for clarity. It will be needed to turn on the MSD during starting.