It does look like you'll have some clearance issues with nut. The varitube 510 is pretty much the same as the FDV one but with different
threads. It kind of makes
sense why they went with a press fitted 510 now as there probably wasn't enough space to put a threaded one in there with that second board. I wonder what that board is for then? My friend that I've mentioned about in earlier posts told me that his
ipv also had that second board in there. He assumed it was the touch sensor and it just wasn't hooked up.
If you have a dial caliper you can measure the space where the 510 is at. I can measure how wide the FDV nut is as well and we can see if it will work.