There is no limit on the amounts that can be received by US residents from foreign individuals.
There is no tax on an inheritance received from a non-resident individual. If the inheritance is in excess of $100,000, the recipient is required to file an informational form to show where the funds came from. I have included a link to Form 3520 and instructions below.
The form deals gifts, trusts, and distributions, and in all cases, they are taxable.
There is no US tax on an inheritance from a foreign estate.
In the instructions, item 4(a) relates to amount inherited.
The purpose of the form is to put the government on notice that a US resident has received funds from a foreign estate.
The financial institutions report information about certain deposits, this provides them with the depositors side of the transaction.
Under "Who Must File" Item #4a is for US residents (you) to report amounts received from a foreign estate (your father's) if the amount received is in excess of $100,000.