I have an unused alloy 505 boom which would probably do - It is in Norfolk - Its a Proctor one -  similar dimensions to my Super Spar but possibly a bit beefier sideways.

"Does anyone have an ally boom sitting around to suit a 2503 foot main? \r\n\r\nNeeded to convert an old sail plan to accept the more modern format.\r\n\r\nIf you could let me know what you have, where it is and how much you want that would be helpful!\r\n\r\nThanks"

I have a super spar Ali boom I am looking to sell. Plus two poles.. \r\n\r\nGreat condition.