In fact, the good thing would be to use this Morane with the Forgotten nation mod... as a specific CH airplane, available only if you select Switzerland, ans not modifying other nations...
I read in books that the D-3800 was in fact a MS.405 with a 12Y31 engine (the standard 406 engine, instead of the 12Ycrs of 12Ygrs of the 405) and that the D-3801 had the more powerful 12Y51, never installed in M.S. 405/406/410s. It seems strange at first (to revert back to the older airframe), but the changes from the 405 to 406 were a failure; the lighter wings shaked badly at dive speeds, the radiator if for any reason was broken (e.g. a gun hit) was locked in the closed position (= overheating and engine failure). So my point is that M.S. 40x and D-380x were not identical.