Brakes and suspension entirely depends how far you want to go tbh. A lot of people keep leaf springs with success, especially for an entirely road based car, but 5 linking and coilovers undoubtedly offers better location (but significant expense the the complication of potential IVA implications).

For the front, the biggest problem is the antiroll bar, which also acts as the tie rods to the front crossmember. The simplest mod is an addition mount in the centre of the crossmember to remove some of the bending, but after this youre into compression struts and a separate antiroll bar.