I am 92kgs and always just used to have 90lt wave boards for east coast.
About 5 yrs ago I got a 100lt. What a huge difference those extra litres make when it comes to light wind days and big surf and getting over the white water.
You loose out a bit on the waves as they bounce a bit more but on a smaller board I probably would not have even made it out the back(beach break)!
I currently am using a 100lt Evo but am getting a Nude custom twin 100lt made up at the moment.
My small board is an 80lt ET.
There are not many production big wave boards and they are expensive.
rrd make 99lt twin, JP have a 92lt twin,Fanatic twin 92lt?, most are less than 90lt or are more freestyle/wave boards.
Last Jan at Margs there were plenty of big guys on 100+ lt boards ripping(Corey and others).
Go the extra 10lt above your weight, you will not regret it.
If you think its too big then drink more beer, problem fixed