There are several good candidates for L554 testing (in order of relatedness):
1) All eleven submissions with 8 of 12 fingerprint matches should be tested even that most will probably test negative. See the L554 link under DNA Results for these testing candidates: Parsons (175486), McFarlane (154169), McAlister (23488), MacFarlane (9FBYZ), Miles (YD7B4), Enyart (ZHAKK), Ranney (Y2F4B), Wilson (103206), Everett (115552) and Williams (N9495).
2) Since 487 >= 14 is key to the L554 and is pretty rare in transitional matches (between 50 and 70 %), testing submissions with reasonable mutational difference is recommended. Submission 122217 (Bonham) is one of the better testing candidates.
The DNA results spreadsheet includes around ten very good testing candidates. The fingerprint of L554 is pretty speculative since there are only three positive tests to date, negative test results near 70 % matches and significant mutational difference between most testing candidates. These characteristics suggest significant overlap between positive and negative test results should be expected in the transitional area (between 50 and 70 % matches of the L554 fingerprint).