Can I use a larger HVAC Hard Start kit than is recommended?
Does your compressor start now? If it does, adding a hard start kit does absolutely nothing beneficial for you and in fact might be harmful. The original intent of a hard start kit was to compensate for voltage drop in the wiring by the time it gets out to a compressor, especially in areas where the utility supply may drop during high use days (i.e. all of your neighbors are home using their AC systems). But for the people who make them, that was not enough sales volume, so they "invented" a problem needing a solution. Their claim is that a compressor starts with high current and that this is damaging the compressor; which is an utter falsehood. The 5-2-1 sales literature starts out with a LIE! It states that "Amps x Volts = wattage" and that wattage is what you pay for. So per their concept, when the starting current goes to 600% (they say 700% witch is an exaggeration), the watts go up so high that the motor over heats. The lie is that watts = amps x volts x POWER FACTOR, and when a motor first starts, the power factor is extremely low. So for example if your 230V motor draws 10A when running, and the PF = 80%, the watts used is 230 x 10 x .8 or 1840W. On starting though, it is going to be 60A x 230V, but the PF is .2, so the watts are 2760, not 13,800 as they would claim.

What the "hard start" kit does is add another capacitor to the motor only for start-up, which compensates for the low power factor, then automatically switches it out of the circuit when the motor gets to 80% speed, usually less than 1 second. It ALSO increases the voltage, which increases the torque, which can be potentially DAMAGING to the compressor. They don't tell you that part!

Hard start kits have a legitimate purpose, but making your compressor last longer when it is not having trouble starting is bogus.

As to your question; yes, if you use a hard start kit intended for a larger motor, it can INCREASE that potential for excess torque damage.