CA glue in some 1" triangle stick. Use P1 to get the center location. Use a clamp to get the angle and only glue where the sticks cross and where they touch P2.

P1 is a departure from the original nose opening look because of ease and engine selection. However, if you want to build-up the more triangler look nose, move the triangle sticks back as for as the engine will allow and fit P1 at this location. Add balsa to shape the nose for the ply wrap.