Checking the timing a good idea. Did consider mentioning it when I penned my previous reply. Matching the timing to modern fuel may mean a small difference to factory figures. Make sure your advance mechanism is working smoothly. Sticking in an advanced position that doesn't match the engine speed can make for poor running.
Return springs on the carbs might be incorrect or weak. Pedal feel is proportional to the strength of the springs. Sometimes the mounting tabs at the manifold end are incorrectly mounted which can give a weak spring effect.