It's 99 percent a 359.
First most obvious thing is the labels on the cover, 346/353 are placed front to back, 357/359 are side by side. Also the straight across muffler screws/bracket. Felling sight is interrupted in the middle by the 'H' logo on 346's.
Then there's a little circle cast into the fin in front of the decomp, 357's don't have that.
<Edit> Looked at that circle on the cylinder fin again, now not so sure that's what it is.
The one on the 359 would be higher up, more likely just a reflection I'm seeing here. So maybe a 357...
There's endless reasons why it's not a 455...