my bad, didnt read that part,
unless your really good at alluminium tig welding or tig welding in general i wouldnt even try to attempt it yourself, has to be done spot on, able to with stand pressure and also be pressure tested to ensure your not going to have any leaks.
as nismoid said, if you intend on tracking it then y would u do a half assed job, get it done correct 1st time n have some peace of mind