Just use a dowl.
Use rods on each end of the dowl.
drill acnhor hole on each end of the dowl...(but not required.) 1"-2" from the ends of course.
Wrap the rods with threads and CA it.

Or you can just soilder two rods together. if your have a torch and proper soilder (silver)

or you can use those rods couplings ..mmm, like what's on my Raptor for the tail rotor.

Or you use wheel collars to couple the rods....that's how they want you to do it on my cap232.
But i trusted my friend's soilder skills better.lol nah..he had a torch.

It'll be easier if you install the push rods before mounting the engine, fuel tank..etc.
This way you can sholve the rods through the firewall opening. it'll be easier for you
to navigate the rod to exit through the fuselage.