Some help,

What you should be asking yourself is "Is this really a good idea". Personally I'd answer that as a no. While I've never worn anything like this helm you speak of I do know that in general heads built upon helmet type contravences tend to be heavy, and very very hot. You are going to go through a whole lot of trouble just to modify and built upon and what for? A head you cannot even wear for very long.

Leave your goalie's helm back on the shelf. If you want to make a fur-suit head you need to do so with a wiser base. You can get a cheap foam head off somethiing like amazon and match it up to your own head's specs. Use that and built a base out of what techinique you feel like trying. There is an all mesh technique, a wire technique and both are great for beginners. There is also the baklava mask techinque where put it on a dummy head and built up upon with foam and use elastic to create a jaw strap.

*sometimes people use helmets for bases of quad-suits but really over all it's not the best idea for a head in general.

with refrence to the above post, i also have no clue how well that would work, but i have an idea, if you want to/can do it try making plastic "ear guards" and turn the face mask into a "muzzle mask"  and build your "suit" around hockey, if you still like hockey that is.

Ok so I guess it wasn't a good idea. I'll put it back on the shelf. Thanks though for the feedback on it!