All,
While many people on here can braze or weld steel joints together, aluminium welding is a higher level of difficulty which not everyone has reached....
For this reason, I went to Olliminium (http://olliminium.com/), based at Bicester Heritage in one of the restored huts there, to weld some brackets to an aluminium cooling pipe. Ollie is a really friendly guy, and did a really nice job (I'll add a photo later) for a really reasonable price.
Hope your rebuilds are going well,
Tom