Assigning each letter of the alphabet the numerical values of its position in the alphabet (a=1, b=2, c=3, etc) find a familiar first name witha product of letter values that is equal to 100,000.

To find a familiar first name with a product of letter values equal to 100,000, we'll need to calculate the product of letter values for each letter in the name.

Here's how you can approach this using Python:

1. Create a list or a dictionary containing the numerical values for each letter of the alphabet. For example, in Python, you can create a dictionary where the keys are the letters, and the values are their corresponding numerical values.

```python
letter_values = {'a': 1, 'b': 2, 'c': 3, ..., 'z': 26}
```

2. Iterate through common first names and calculate the product of their letter values until you find the desired result. You can find a list of common first names online or use an existing dataset.

```python
import string

for name in common_names:
product = 1
for letter in name.lower():
product *= letter_values.get(letter, 1) # Using 1 as default value in case the letter is not in the dictionary

if product == 100000:
print(name)
break
```

In the code above, we assume you have a list or a variable called `common_names` that holds the list of common first names you can iterate over. We calculate the product of the letter values for each name and compare it to the target value of 100,000. If it matches, we print the name and break out of the loop.

Keep in mind that finding a familiar first name that satisfies the condition exactly might be difficult. You may need to adjust the target value or explore different combinations of algorithms and datasets to find a suitable name.