From memory the hole space and dimensions of the bolt to retain them are the same across all three models.
The difference between the calliper, apart from how the hoses connect, is that the casting is deeper on the internal sides of the calliper to accommodate the thicker discs for vented. In practice you could accurately machine a spacer to put between the two halves to convert from solid to vented. I mocked some up once .
I've fitted solid disc 244 disc callipers to a 1800 front also. In order to have removable discs at the front, and more available parts….back then. The 240 hub has two be adapted, but interestingly the callipers bolt right up.
the rears are basically interchangeable.
Hope this helps.
