As a diver you will know that a too short wetsuit is just a pain in the Ba$%s. Its much worse with surfing, because there is a lot more movement and jumping around and stuff. You dont want to risk it.
A few brands make 'T' models ('T' for tall) although a lot of them only do MT and LT. However, Xcel do an XLT
http://us.shop.xcelwetsuits.com/images/ ... eChart.pdf as do RipCurl and O'Neill (and probably some others). I know they generally max out at 220lb, but there is a bit of give and take in the weight category due to stretch.
The higher up the line you get in wetsuits, the stretchier they are. But most of the stretch is designed 'horizontally' ie to give stretch around the shoulders or stomach, rather than vertically (more height) - for example, a back zip will restrict vertical stretching because the fabric is sewn into the zip and can't move upwards. Front zip wetsuits are way more comfortable if you are a larger guy, because the lack of back zip (the front zip is horizontal across the chest) means there is a lot more stretch available and it can go vertical. But front zips are waaay harder to take off (to the extent of almost being embarrassing)! Still - if you need some vertical stretch, then front zips are the way to go.
A little extra weight over the spec sheet shouldnt be an issue - the suit will stretch and being a bit tight around (say) the waist is much more comfortable than too short around the nether regions. That said, too tight around the shoulders is a problem
Obviously, if you can try them on then do so. Each make is different around the shoulders etc. For example, while I nominally fitted the XL specs for most of the brands, I found that Xcel was the only cut that actually fitted me around the shoulders.
Summary:
- look for XLT size
- front zip
- higher spec (most front zips are higher spec anyway). No need to go highest spec, but say 2nd or 3rd level down.