If the "upper VHF bands, into the 140's" that paragliders use are the Amateur Radio frequencies (144-146MHz in UK), then the problem is that aircraft VHF transceivers use AM whereas the Amateur bands (and Marine/Police etc) use FM. You will not find a transceiver that works on both modes. FM receivers can receive aircraft AM transmissions, but for transmitting, it has to be the right system. (As far as I know.....)