Need to know whether you have a gas/petrol or diesel engine, and also, if you're in Europe, if you have the diesel engine with the DPF.
Displacement does not correspond to horsepower. A 1500cc engine made in the 1960s was much less advanced, and will not be as powerful as a 1500cc engine made in 2015. Give a specific engine model, and answering this question will be much more feasible
location of overflow vent on 1972 VW Beetle IRS rear suspension