Brad's bike is a magnum with 490, engine, forks, swing arm and shocks. Although I think Brad has got foreign forks on the bike. The bike sits lower than the 81. In some respects it is a replica of the 1979 works bike in VMX, except that one is a 250. But again that bike appears to have a pre-production 1981 frame. You can even see the lower bracket for the full side cover for an 1981. To me it still raises the question WHY did Maico make the 1980 model the way they did and not just update the 1979. Don't get me wrong the 1980 440 was still a reasonable bike, but nowhere near the 1981 490 or probably a updated 1979 model.
Which handles better? Probably the 1979 mainly because it sits lower. It can also be argued that a 1977 model steers and handles better than them all.
Just a side note I remember racing against Paul Stacker at a Thumper Nats once at Albury. His bike was a magnum with mega 2 forks, swingarm, shocks etc. It was probably taken out to 490 also.
Kevin