Hello Alex,
I've fired off an email to the FAA asking them for their opinion. We have so many of these questions, and their take on most STC mods is that if the modification of the aircraft has not changed the model designation (your J model is still a J) , and there are no adverse flight characteristics, then it is ok (with the prop clearance thing we'd mentioned). I'll let you know what they say. The 3190 is approved to 2950 on your J model as is, and there is no difference between the installation for the 180 and the 185, which is approved to 3320, so the floats will take it just fine. Sorry we can't give you a definitive answer, but the world of STCs is a foggy place.
Best Regards,
Helen and Terry Claggett
Aqua Float Company