Check the Underground website as they have a board picker function
I put in your specs on the website and it spat out the FLX for you.
I bought a FLX 32 after riding a friends FLX 28. I am 73Kg and decided to go with the 32 b/c the summers here can get light and I like a little longer edge to carve my turns on. Depending on how fast you are progressing and the conditions you ride in, you might consider the 32 b/c you are not that heavy. Although a 32 is considered a short board I would say the FLX 32 is bordering on medium length feel since its a full 39 wide.
The problem with going too big (say 42) is that its harder to stomp the back foot for braking when you are out in windier conditions (20-25+). The UG FLX will hold the edge but you'll be really flying and on the seat of your pants!
In summary, I am very positive about UG FLX series as they are fast,
light, hold their edge well, eat up chop (flexy tips) and look super cool