You have a good gun there, well looked after and capable of winning competitions, with plenty of practice of course!!
I used to have a riser block glued to the underside and also a tie on suede leather hampster for added height. I believe I still have both knocking around somewhere so will have a look and let Steve have them when I see him sunday. You may like to borrow and try and see if that solution suits you before making something!!
Found an old picture to show you what it was like.
AA Field Target Team 2007~2011
East Devon FTC - SWEFTA Club Champions 2006/2007/2008/2009/2010 & 2013/2014/2015