I go along with COPB on the "I" beam for front axle, and you must be able to adjust Caster and Camber as needed easily.
I dont know of any "STOCK" components that I would feel safe with at the speeds you are looking for. Definitly much larger Spindles with HD backing to take the stress.
I am real suspicious of EZ GO spring mounts for this kind of speeds again. You should use adjustable springs and shocks for safety sake.
Some type of HD wheels and of course high speed tires, even some auto tires are not good for the high speed used.
I feel that some type of HD shielding should be around the motor and very much so the axle that you use. ( I dont think that the stock differentials that are available for Golf Cars are safe enough for your use?) I know that we have all used stock parts to save money and ease of installation BUT, after loosing 2 relatives to stock parts damage I think something on the order of what is required for NHRA drag racing would be good. I have seen too many parts come up through floors or out into crowds to not want some kind of protection? Thats my 75 year old 2 Cents worth??
Good luck on your project and I hope you keep us posted with photo's along the way.