I'd warn against taking Boromir at games below 600-700 pts to be honest. Additionally, your numbers are too low and you have a few points sinks (horn + banner, just pick one) as well as expensive troops. I'd suggest beregond leading 6 WOMT with either 6 spear WOMT or rangers to support them. I'd duplicate this warband for others to lead as well (if you have Damrod or Denethor use these). Replace boromir with cirion or Faramir.
If you play Gondor at 450 points, you could easily get over 40 models on the table if you use cheap heroes. It's a major benefit. If you want to sprinkle some S3 bows and fountain court guard around your warbands then feel free, but remember that Gondor's advantage at lower points games lies in cheap heroes and therefore cheap warbands. (Edit* and maxing out the bow limit)
If you want help in forming a list, I'd be happy to help.