I came across this bolt on hardtail the other day on the Acme site that said it fitted any triumph and was wondering the same thing. I am overseas for a while so can't check my speedy to see if it would, good price though.

http://www.acmechoppers.net/index.php?l=product_detail&p=132

I would like to try and get a plunger frame so I get a bit of suspension