More than one thing to consider there. Arm needs to be away from back of opening when clutch fully loose. Arm must also be in a position to be able to use maximum adjustment of either cable or solid linkage pushing on it. Does no good putting it in the middle of hole if then you only have very little adjustment on a new clutch. If motor is out so you can play, then bolt trans to motor and check by turning trans output while in gear, slowly move lever back until clutch releases cleanly and then a bit more and see where in opening that all ends up. You don't want a whopping amount of over travel when pushing on pressure plate, depending on the type (diaphragm) you can go too far and pressure plate then goes over center to stick and then does not come back. When fully released the arm must allow some freeplay too, maybe 1/2" at clutch pedal itself is good, otherwise the throwout bearing wears like lightning.

Now, try getting all that in one package. Fun.