Cool block. I've been making a lucky block mod myself.
Might i say though, 125 drops isn't THAT much. it's like the default lucky block, but with a few OP extra's. i would aim for a fewwww more, like 200 at least.
Also, if you make a 1.8.9 (or lower) version you could have more options for things like custom block/item drops. Loot++ is a great mod to add you're own blocks and things, without having to know any real code (just follow pre-written tutorials in the mod addon's folder once you play a with it once).
And for the block texture, while it looks fine, it would be cool if you added a creeper face, just to add to the "creeper-ness" of the block. you could make the creeper face directly on the block, then put the question mark on top as an overlay. Just a suggestion that might look better (but who knows, might look awful) xD