How do i prep this rudist?

[Hapchazzard]

So, I've got this early Maastrichtean rudist, and I'm looking for a good way to get it in a presentable shape, preferably without having to use expensive equipment. The matrix is limestone, though not soft enough to be simply peeled away with a brush. I'm not sure whether using vinegar would be a smart idea - I have a feeling that it would damage the fossil. Also, what would be the best way to reattach the two separate parts together?

 

I thank anyone giving input in advance.