Don't you just love the torque of a reed valve saw? I have a couple of old P45s, same as your 455 but not as pretty. Mine are real pigs on fuel consumption, as was my P42. That's one reason I don't use them very much. Wondering if you 455 is like that.
And heck yes, I'm willing to share anything I know. But I'm a little burnt out right now from a guy being snotty on another site when I shared some proven chain filing secrets. (The little video above gives you an idea of the results I'm talking about.)
I'm using some old velocity stacks, milled from aluminum, that I bought as aftermarket items from a Pioneer dealer in the early 80s. I have what I think is an improved design that I'm seeing about getting 3-D printed, and I hope to get some made for guys like you. And I don't intend to make any money on them.