Performing a dictionary attack on RSA/ECB with no padding
If the public modulus was generated properly, option 2 (brute force dictionary search of candidate plaintext) will be faster. Option 1 (factoring a ≈512-bit RSA integer) is feasible, but can be quite compute-intensive even with the best known algorithm (GNFS). On the other hand, if random padding was used (as it should, and would be in any good practice), option 2 would not be feasible.

First things are to determine how exactly a dictionary word would be encrypted, including formatting of the ciphertext.

I think Python 3 might be acceptably fast just checking if pow(m,e,n)==c where m varies over the plaintexts appropriately converted to integer as in the encrption, and c is the ciphertext appropriately converted back to integer. For (perhaps only slightly) better speed, write a compiled program using GMP.