[40 Deluxe]

1. Does the trans have a vacuum modulator on the rear of the case? Is so, that throttle linkage is just for full throttle kickdown. If no vacuum diaphragm, that throttle linkage is critical for proper shifting and trans life. Adjust per shop manual. If your trans is from that '56 T-Bird, it will not have a modulator and the throttle linkage must be stock (or function exactly like stock) and be kept properly adjusted.
2. If your distributor is the original '56 dual diaphragm unit, you have the wrong carb! The OEM distributor is vacuum advance only and needs the OEM carb. or the spark advance won't work. That late model Holley will work fine with a '57 and up Y-block distributor.
3. Don't forget that the 312 (and all Y-blocks) are solid lifter engines and need periodic valve adjustments.
4. The rest is basic maintenance and troubleshooting.