I have been reading this forums for years, and apparently only posted in this threat... shows how lazy I am, or how much I want a Gargant list

Cheaper Gargant sounds good (although 550 might be too cheap, 600 better?). For the Wyrdboy Tower I would prefer 2 shots over D3 shots - orkz already have quite a lot of randomness, and always first rolling for the number of shots whenever a plane approaches might be unneccessarily tiresome.
I also agree now that a dread/Stompa formation is not needed in this list.
What I think are the main concerns, and which solutions I want to suggest:
1. Weapons. They are too few, and upgrading is not very intuitive.
I would add more guns, mainly the guns from the old 3.05 list plus some AT (e.g. Death arsenal - 90cm - 3*AT 4+) and some fancy shortrange stuff (e.g. flamer: 30 cm BP weapon with IC, or Shock Attack Gun battery: BP weapon with disrupt)
Then, I would classify them as Special Guns and Mega guns as they have different power levels (e.g. Lifta Droppa is better than the Mega Choppa, Twin Soopa Gun is better than Supa Gun etc.) Let the Gargant chose 3 weapons from the weaker Special Guns list, the Great Gargant can also chose 3 weapons, but up to 2 can be chosen from the stronger Mega Guns list.
In addition, allow 0-1 Kustom job: either upgrade a Special Gun to a Mega gun, or get one of the additional benefits that do not replace a weapon (e.g. Wyrdboy tower)
2. Speed. Everything with speed 15 cm is a bit boring.
Fortresses are rarely taken, as they are so squishy. In the Gargant list they might shine. Maybe allow a formation of 1/2/3 Fortresses. To emphasize the Mek-style of the list, give it some special weapons like the custom cannon (45cm MW4+) and/or force it to take an Oddboy upgrade.
I am quite busy this week, but if desired maybe at the weekend I can compile a short draft to make a bit more clear what I mean.