You definitely would want to consider using a
sump for a tank that size, it's a great place to hide the
skimmer and
refugium should you choose to go with either of these. Your heaters are fine, but most people choose to not use
HOB filters and instead use the
live rock as the filter, far superior in every regard. Another huge concern is lighting requirements should you choose to keep coral, a tank that size will need quite a bit of light. Just some considerations. Read, read, and read some more, theres always more to learn.
Dave