David, do you have the parts listing for that engine? It may be that the FS 70 Ultimate case would work, and it is showing Pending on Towers site. Also if you look for the part, by O.S. part number, you may find it.

Repost your question on the O.S. support forum and see what Bax has to say. I'm sure he isn't going to recommend trying the Magnum case as it isn't an O.S. part, but may have a source for the part.

The magnum engines are clones of the Pre Surpass engines, or at least the Surpass I with the silver head. I've got a Mag 70 but I don't want to tear it down for a comparison.

You may check to see if the bearing are the same between the Mag and O.S. Also check the size of the cam bearings. If those are the same size, your prospects look better that the Mag case will work. I would check the lifter size also, but you could use the mag lifters if the height is very close.

Don