To Firko and miniwheels Thanks,
It is refreshing to hear from guys who get it. Firko, you are one of the most observant guys I know, and you are correct the tank I used for my 250 scrambler is in fact a magnum tank. I had to cut the center channel out add about 1" to lift the front up. The swing arm is not alloy but rather a nickel plated later model arm. The neat thing about maico is this started a 1957 motor but I was able to put in 1981 clutch plates using 1974 250 clutch basket, primary gear and crank shaft. After a little machine work to the center cases I was able to fit the more reliable "t" trans from the square barrel. AHRMA rules only allows you to use a two cone pipe, no center section, not a problem the 1977 AW 250 low pipe does not have a center cone. What I have done to the cylinder is top secret and you will have to email me to get that info, but I will tell you one thing it will run with the square barrels. About the 250 and 360 oval barrels the ones I have where hard to find and expensive and there are on my race bikes. Jim McCabe who I believe is no longer with us? unless I am wrong was or is? an oval barrel hoarder and did have lots of those cylinders but no one could ever get them out of him. Anyway I like your sprite idea for a maico motor swap.
Cheers
Karl