The blocks I would be wary of are those that use Dynamic type. Unfortunately, that includes several of the most common and useful ones: any blocks that work with data that isn't required to be one specific type. These include the game attribute blocks, the 'get value' blocks in the Behaviors palette, and actor value blocks.
The proper solution would be to not use Dynamic, but that won't be an option if you want to use the blocks. I'm not sure if this would work--but you might be able to store your larger numbers as strings and always concatenate a ".0" when storing them. To do math, you'll need to convert to float (the number attributes are okay for this), do your math, then convert back to a string (with ".0" concatenated) to store the data. Managing the data this way will be significantly slower, but the speed difference is still negligible if you're using huge numbers to store a score, resource counts, or any other data that doesn't need to be accessed thousands of times per frame.
I don't know what Haxe targets this would work on, if any. It's just an idea I pulled off the top of my head. It's a common trick to force floating point math in computer algebra systems (like Mathematica, Wolfram Alpha, Maple) that don't require numeric variables to have types at all... or abstract that from the user.