Aussie A Body Chassis Strengthening

I have An Australan Valant Charger 108 Wheelbase, I want to strengthen Also looking at getting rid of the steering box and fittng rack and Pinion , I am going to be running an RB 383

Just Wondering what Peoples suggestions are ,

1, Wondering what rack is commonly used , read somewhere a Dodge Omni was useable or a Ford Mustang????

I have seen some chassis kit s online , But How much of a Kit do I need , Just Rail Sleeves ??