Sorry to add a new wrinkle to this, but something else to consider from someone in a similar boat as you;
I have a 23.5 inch head as well, and my journey to find the perfect H1 was long and frustrating. From the NO Shat/Creep to the 2K, 98 Proto, 75K, Nightstalker, Vintage 75, Unleashed 75…(there may be others but memory fails at the moment), my journey finally ended with the 75K Castle. After trying on various masks and never seeing “it”; that look you associate with the way Michael looks in H1 that was never duplicated on screen again, I concluded my head size just wasn’t gonna pull it off. I seemed to “Warlock” every H1 mask I put on. Then, after having a conversation with Nik about sizing and whatnot he mentioned to me he has the 75K Castle in a larger 25" option.
I talked it over with James Carter to get his opinion, as my spot was coming up with him and I wanted to make this H1 count. James had the opinion the 25" was gonna be too big and it was his feeling I should consider a smaller option. And when James tells you something about a mask, any mask, your brain tends to kick you in the ass and order you to do whatever he says, and with good reason. The man has seen a mask or two and knows what he’s talking about. But, in this case, after having tried so many different masks and seeing my eyes practically pressed against the eye holes and having virtually no extra room inside, I went with my gut and ordered the 25" Castle and I specified a “slightly thicker pull” to try to avoid having too much room on the inside. And even then, if the mask was too big, I could easily remedy by wearing a beanie. But, what you can’t fix is it being too small which I had been through too many times, so I pulled the trigger on that 25, and Brother, it was the best decision I could’ve possibly made. The mask fits PERFECT and finally, I feel like I capture the essence of Nick Castle when I wear it. I don’t even need the beanie. I just put it on and go. It slides right on with no problem and is easy to take off. This is my H1 grail, and I wouldn’t sell it for $5,000. It took me five years, but I finally got there.
There was an initial worry about would this mask be too big and make my head look too large for my body. I wear size 48 in Red Kap coveralls, as I have more of a Jason body than vintage Michael, and the large Castle mask is perfectly proportioned and blends right in with the rest of me. I love it and I’m so glad I rolled the dice on the large version. I feel like anything less would’ve just missed the look I was hoping for.
Here’s a worn shot. Ignore the hair. I didn’t really spend any time on it before I got a few test shots. Hope this helps you make a decision, and good luck.