[heskahoka]

What a coincidence, I just finished the swap of my 307 2bbl for a 350 and Edelbrock 4bbl in my 68. I did end up reusing the existing factory throttle rod.

Here is what I did:
For the throttle return spring, I bought a Mr. Gasket 9678 throttle return spring kit. (See Pic).
It mounted fine on the front drivers side carb stud (after a bit of trimming on the Mr Gasket mount bracket).

The return springs attach to the included Mr. Gasket swivel mount which I attached to the Edelbrock throttle bracket 'large hole' using the included hardware.

The factory throttle rod end then went into the 'smaller hole' on the carb linkage after I drilled it out slightly. (See pic.)

I have not secured that end into the Edelbrock linkage because, once everything was tightened down, I could not get it to slip out of the hole, even by putting side force on the rod. Lubed up the joints and everything is good.

Good luck on your install.