Identifying your bike will not be too much of an issue if you can post a series of photos of it.
The thumbnail is simply too small to work with.
There will be a thread here somewhere if you are having trouble, you normally require the image details from a Photobucket account or similar.
From the thumbnail the bike appears to have 1967/1968 parts and features. It may have an earlier engine fitted for that A50B number. The later frames had the frame number down by the left front engine mount. I would expect to see yours there and possibly on a flattened boss.