I've been looking for an existing reticle that provides the proper oval mask to match the reflector glass shape. This one fits the best.

<Effect Type="Track" EffectName="uk_raf_bob2-_gunsight" PosX="0" PosZ="-0.825" PosY="0.9725" Pitch="90.0" MinVel="-999999" MaxVel="999999"/>

The next best is

<Effect Type="Track" EffectName="us_aaf_l3-_gunsight" PosX="0" PosZ="-0.725" PosY="0.9725" Pitch="90.0" MinVel="-999999" MaxVel="999999"/>

If we want this aircraft to have the K14 reticle (like the static default) I can create a new dds file with a texture mask like the one in BOB2-, but there will have to be a new line added to the effects.xml file, and some people may not care to do the edit required for it to work.