The Monogram kit's tail looks too short, a problem nobody even knew about before Meng came up with their kit... I had no clue...
This does not exclude the Meng kit being slightly too long (which I think is likely), but its tail does look more slender and a bit more like the real thing's photo, while the smaller uncovered drawing (which I assume is identical to the bigger reference drawing) looks wrong in the tail section, although by how much remains to be seen.
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The following is by no means definitive, but just a rough indication of scale proportionality measured from the above photos: I took the longuest easily definable elements (canopy length and canopy distance to fin), to minimize measurement errors, and compared them in ratios: Remember that if the online reproduction of the photo is distorted, this does not change the ratios.
The completed Monogram kit photo: 42.5 mm/53.5 mm: Canopy/tail ratio: 1.25
Monogram fuselage half photo: 58 mm/72.5 mm: Canopy tail ratio: 1.25
Actual aircraft photo: 49 mm/66 mm: Canopy/tail ratio: 1.34
I would add 1 mm to the tail (67 mm) to account for the lens position's perspective effect: The canopy/tail Ratio would then be 1.36...
Meng kit fuselage half photo: 54.5 mm/76.5 mm: Canopy/tail ratio: 1.40
So it would appear, assuming the canopies are equal and correct, that the Monogram's tail is proportionately too short, while the Meng's tail is proportionately too long.
However, 1.40 is much closer to 1.34 or 1.36 than Monogram at 1.25.
This is just to give a rough idea. If confirmed, it is worthy of noting that it is easier to shorten a kit than to lenghten it...
Another thing to note is that a kit is always a far more serious investment than a drawing, and the usual assumption that a drawing carries more authority (especially factory GA drawings) is almost always a wrong assumption: I have hardly ever seen drawings that were correct in general outlines, and far more kits that were excellent...
Since, in the peculiar case of the Me-410, we don't even know what the actual fuselage length is, without those pesky engines in the way, it hard to tell what is wrong with the drawings, but they certainly don't look right in the tail.
While the Meng kit appears to have minor problems (notably the extremity of its nose), it still looks by far like the better kit of the two.
Gaston