I suspect you will have to block those holes to get the T slot position correct.
318 has more cubes, so needs more idle air, hence holes in blades.
I would not trust epoxy to block the holes. A tiny nut & bolt, Loctited and/or staked works well. You can also soft solder, resin cored solder. Although the solder has a low melting point, it is still much higher than the engine temp, so no problem. I have used both methods many times, no problems. I would NOT weld the blades, too much chance of distorting the thin metal from welding heat, upsetting the critical T slot position.