I did Samoa for a week in june last year.
There was very limited access for rock hopping,

there was a loop rode we traveled but couldnt find a decent spot to access without swell.
There where a few spots about but its luck of the draw with the swell.

I ended going out on a boat for the day to a reef a few miles out from the port.
there where a few cuta and trevs about but for me they where hanging below my max range.

120 should be fine.
I shoot most things in the tropics with a 120.

Up to you what you would rather carry.

Ask for Trevor Meredith when you get here....
He's the speer fisho "Dive Guy" here I Samoa...
Hope that helps