Not connected with real Icom but a 40-channel 27/81 CB with the MC145106 synthesizer that could be easily converted to 29MHz.
The original notes were taken from an article published in Short Wave Magazine by G3XSE. These allowed a quick conversion on to 29MHz by moving a few wires. I improved on these by changing the synthesizer steps from 10kHz to 5kHz and adding a +5kHz offset switch. The disadvantage of this method is that the 40 channels do not all run sequentially, you will have to figure those out for yourself! Later SWM articles by G4LBW used additional boards using 4008 cmos binary adders to give a repeater offset and correct the display.