The whitemetal kit parts for the bodywork are not likely to pose insurmountable problems if you already have modelling skills. Patience, cleaning up the parts, and assembly on a flat surface with a set square; and reference to drawings and photographs should bring the job in. But for the powered chassis let me suggest a heretical thought. It is worth researching what is available in RTR form that might match the chassis of the Jones goods and fit entire within the whitemetal body , for the simple reason that even purchasing a whole RTR model to acquire the chassis may be little different in cost than the wheels, motor and gearbox to complete a kit chassis. Surplus parts from the RTR model can be readily sold in my experience (people damage their models just for a start) and that brings the cost down further.