If I may...
If the 350 ampere alternator is from Ford, fine and dandy. You will absolutely have to go to the recommended super wide serpentine belt to drive that intense of a load. 1-AWG Is fine up to 10' in length.
Remanufactured 3, 4, & 6-G alternators that boast hopped-up amperage are garbage. Low speed amperage disappears. In a 6 inch case only a ND HAIRPIN alternator will work correctly. Even the haipins should utilize an external rectifier.
Overcooked hopped up alternators remind me of the VW bug craze of the 60's and 70's.
Take a beetle. Spend 1500 dollars on modified engine internals. Get maybe 85 hp
Fuel mileage drops to 15. A Ford Mustang would run circles around it, get better mileage, and not eat the drivetrain due to power.
Use wisdom when planning upgrades.