That's superb!
One question: how did you prep the toy for painting? My son has a fair number of Schleich/Papo dinosaurs that he's more or less grown out of and which I've suggested reincarnating as HotT behemoths and the like ...
Thanks for the kind words everyone
First photo says it all: just regular spray primer. It seems rugged enough, as I handled the model a lot with a nitrile-gloved hand while painting and nothing wore off. Toy paint is super durable and if the primer layer sticks to that, I think the paint job is going to hold fast.
Another issue I should mention is the embossed "CE" and "Made in Germany" lettering on the belly and inner legs. Not hugely visible, but for a display model I felt compelled to cover some of it with a thin putty layer of belly scales, and file the rest off. It's a pain.