Pennsylvania and New York are both part of a Driver License Compact (DLC) that allows for the member states to report tickets received by motorist back to the state where the license was issued. Each state that takes part in the DLC can have its own rules about how they put this information onto your record or assess points for out of state tickets.
PennDOT has decided to not assess points or record minor traffic violations on your PA driving record that have occurred out of state. So you New York ticket for 15 over the limit should not appear on your PA drivers history or be assigned the normal 3 violation points.
As for the penalties from New York, if the court there told you that there was a fine of $180 plus a drivers assessment fee of $300 then that would be what you have to pay. In NY drivers who are convicted of specific traffic violations will be required to pay an assessment to the DMV. If you must pay this assessment, the DMV will send a statement to you.
In NYS the Driver Responsibility Program applies to all drivers who operate, or operated, a motor vehicle in the State of New York, regardless of the state the motorist is licensed in. The purpose of the Driver Responsibility Program is to prevent the repeated behavior of problem drivers and to improve traffic safety.
In addition to any fines, fees, penalties, or surcharges that you pay for a traffic conviction, you must pay the driver responsibility assessment. The assessment is an amount that you must pay each year for three years. You pay the assessment to the DMV.