Hi George, glad you like it.
This Viper is WAY lot better than previous version....go for it [8D]
The brass base was rescued from my old Viper, were I was using Spring Air if you remember.
It is hold in place with the same screw at he trunium that is holding the centering wire.
For the Spring Air ( which I think you have) I drilled and tapped two 2-56 holes at the trunium front face.....careful should be taken...you don't want to damage the housing for the strut....

Forgot something....the door base are made our of hardwood. I drilled and inserted an small piece of 1/8" brass tube to for the pivoting of the 4-40 rod-axle. Is glued and screw in place. Not removable. Later on will show you how the door is removable.