As with Adrie, I don't think a gasket alone would work.
You can block the lower hole in the crankcase (where you have x), but then need to drill a new drain hole, or the oil level will be too high around the cam.
Oil will then get in through the drain hole to the left of the oil pump (instead of out) and over fill the outer timing cover - no doubt exiting via your magneto...
Aka - a mess.
This is the point of the bent pipe - it keeps the oil level low in the outer cover (by letting it drain to the flywheel cavity) while allowing oil to cover the cam lobe (by blocking the old low drain hole) with the level set via the newly raised drain hole.
While Adrie is correct about needing to split the cases to drill the new drain hole, most of the swarf will go toward the drill. If you were really stuck, contamination could be minimised by drilling very carefully, with grease on the end of the drill bit - and careful washing with the sump plate off.
A more elegant, straight pipe solution would be good, as the bent pipe is a pain to fit. Another thing to take into account if getting creative, is that the bend of the pipe stops it moving in and out (toward or away from the flywheel).
'51,'56 Squares, '48 VH, '27 Model C, R67/2, Mk IV Le Mans, '06 Super Duke and Ariel projects.