After reviewing the table against the spec, two other ideas which be useful:

1. Order the table per the spec ( ie. MCC ordered alphabetically by country )
2. Leave as one MCC per line, and a trailing comment with the country name

Finally, one other possibility to consider is that you could just make the default mnc_length be 2, and just include the 3-digit exceptions in the table.  Note, although more compact, this might make keeping the table in sync with the spec more difficult.