I recommend you keep the Safety Relay, as it's useful in controlling the starter motor operation.
I see in your profile that you have a 1979. The cheapest and best way to up-grade the rectifier and regulator is as follows. Buy a NOS VR-115 automotive regulator, available for less than $23.00................shop around. Buy a 3 phase rectifier, or 2 bridge rectifiers, and make up your own rectifier (heat sink needed)..............cost likely less than $15.00.