Ironwood says goodbye to older bikes with their last carb'd custom. We've also rounded up another fresh Triumph from Tamarit, a Zero with handcrafted bodywork, KTM's new 450 Rally Replica, and a modern homage to the Ducati 750 Sport. Honda GL500 by Ironwood Custom Motorcycles Arjan van den Boom is no stranger to these pages. He’s been making custom bikes since 2012 and has been rather prolific, to say the least. What might come as a surprise, is that you're looking at the last carbureted…