Wow, that's one crazy conversion!!
As for the Betty, I think it can be done. I just enlarged some scale plans of the Osprey Publication on the G4M to 1/48th scale.
The main differences are ofcourse the nose (more glass) and nose cone (different shape)
The adition of the upper turret and the repositioned side guns.
The tailplaines are also larger. All of this seams doable.
The wings looks pretty much the same on both model 11 (Tamiya Kit) and model 22.
the latter had a redisgned wing with was is described as a "laminar flow airfoil" wing.
Thickness and shape look simelar to the wing of a typ 11, the typ 22 has different pannel lines and rounded (larger) wingtips. Ofcourse the typ 22 had different engines and exhaust. Though also this seams doable....
So, there is an itch to scratch here...I have a Tamiya betty in the stash and hopefully I'll be able to find a MXY-7 model 11 Okha (either the trainer of full flying bomd) from Fine Molds.
This would produce quiet a interesting model I think...
Even though the different wing still isn't clear to me yet, but since info on the latter Betty's is pretty scarse, I think I'll go with it. I can always copy the pannel lines of the Hasegawa 1/72 G4M2 (simelar as I did for my Ki-67)
Once I decided which route I'll go, you'll most likely see a new topic in the start to finish build section here