6061,6063,2004,6060 ..ARGHHHH!

Question if I may.......
On the plans of the Homebuilt I am building it calls for a Boom.. The
material requested is 6063-T3 (Which I cannot find anywhere)
After much discussion the designer noted that if you cannot get 6063-T3 you
can use 6061-T6.. Great .. Until I found out I cannot get the length
required in Australia...
After discussing with an Aluminium supplier here they have suggested that I
can use 6060-T5 as a replacement for the 6063-T3 as the length I require is
available in this grade.

Although he would know more than me about aluminium I still feel
uncomfortable with his advice and my lack of knowledge......
Can anyone advise?.. If 6060-T5 is NOT suitable can you suggest a million
other alternatives I can choose from.....

--
Regards

Kevin Berlyn
www.fighterultralight.com
www.australianultralights.com