Suzuki 2 Strokes

Can anyone tell me the differences between RGA500 that raced in 77' and the later RGB500 that raced in 79-80'?

From the Ozebook, it says the rear cylinders were raised, but where there other differences like:
Fairing change
Expansion pipes
Swingarm differences (square/round tubing, braces)
Forks
Wheels
etc

I am building a plastic kit and wondering if I can update the old Matchbox 77' version/kit to a 1979 version
Wish it was the real thing!

http://www.ozebook.com/compendium/suzi/ ... g500b.html

Thanks