42v txt series cart questions

[sand dune coon]

I bought this ezgo (originally 36v)cart from a very old couple that couldn’t tell me much about it. They lived in a golf course community ( with many hills ) and also many golf cart maintenance shops that serviced this retirement community. My thoughts are they probably dropped the cart off at one said shop and said it’s to slow or it dies to soon so that’s why there is the seventh 6v battery, hence the 42v.
Ended up being a 2004 36v series cart with a seventh 6volt Trojans which are in good condition. 42 volt Lester charger also included which is in mint condition.

Looks to me like the controller is the factory upgraded 400 amp controller. So Here is my question,, not sure if the solenoid or FR switch was upgraded when the 42 volt conversion took place, not sure they did anything other than add a battery.
I want to do the 2g cables but trying to get a plan of attack as I don’t want to do this if it’s going to inhibit the F&R and also the solenoid. If the controller is a factory 400 amp controller wouldn’t the FR switch and solenoid also work with the 400 amp controller? Looking to upsize the wires but don’t want to fry anything either.
Thanks in advance.