Realize that the Pyramid kit will not necessarily fit older model C9's soldered valves, such as my 1972 Blue Streak. It fit my sister's HB-20 pistol (1998 vintage) perfectly and is supposed to fit that series Sheridans and Benjamins as well and is worth a try if you have a modicum of mechanical patience/ability.
Accent on the "patience" and internet searching for info/youtube vids a bonus.
Remember that the barrel, valve and chamber are BRASS and are significantly softer than any steel screw you might eventually decide to crossthread into them. I mean it!
Dog