I have Legends God Ginrai, with leg stabilizers. And the PE kits for a transforming Ginrai. He looks pretty nice and has a spot in my main display case. However, he's still horribly unstable and badly in need of an update, IMO.
I actually really like his size. Victory shows him being the same size as, or slightly shorter than, Star Saber. Having him the same size as Victory Saber works really well, though. If anything, he feels a little undersized compared to anyone other than Star Saber, though not by enough to be a problem.
I think keeping an AotP God Ginrai at the same size as Victory Saber should be a good fit for Titan class. The engineering, complexity, and parts count for God Ginrai would have to go way beyond Star Convoy, so there's no way he would be the same size at the same price point.
Outside of doing him as a Titan or HasLab, I'm a little skeptical of how he would turn out. I think they could manage a good Super Ginrai as a Commander. It's God Bomber that worries me. Doing him as a Leader didn't work out real great the last time around, and I think it would be even harder to get a solid release at his size out of a modern Leader. And yet, he would be very underwhelming as a Commander. I think you almost have to have them together as a single set to have it work out well. That pretty much leaves Titan or HasLab as the only options.