No worries Freaky.. you should have said the Antig MX250 frame and there wouldn't have been any confusion. Is it a slider frame you want for your engine or a stock frame? If you want a slider frame, when I've worked out exactly what I'm using I should have one basic Antig frame available with no forks, wheels, tank, bodywork or seat and a set of plates to suit a Yamaha engine. It all depends on the condition of the Maico Antig. I'll let you know when I've worked out which fits what.
As far as the gaskets go, I've got a shitload of Yamaha gaskets Freaky but I'll let you know if I fall short.