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.
upload_2021-7-8_14-49-1.png

Or a slightly more robust layout, still assuming you'll be using an ammeter.
upload_2021-7-8_14-55-45.png

The igntition start wire is only partially drawn in for clarity. It will be needed to turn on the MSD during starting.