Hi. I realise that your original enquiry was a very long time ago, but I wondered if the link below is of any use to you.
Before you check it out, I must stress that it only a model of (presumably), your J3 cub, but it may be of interest anyway.
Regards Mark 07-08-09
Piper Cub - Large scale 106 inch wingspan - 32cc petrol on eBay (end time 09-Aug-09 20:30:00 BST)