It's a fairly straight forward conversion apart from thinking how to mount the strip board PCB.
What I came up with was a 3d printed plate that is mounted through the on/off power switch bolts. Then plate has printed stand offs which raise the pcb just above the switch. See picture 1. The NRF module is mounted on the pcb and uses a pig tail to connect it to the antenna, I wasn't sure if this would affect the range but after a thorough range check I can confirm it has no effect. Range is at least half a mile, I got sick of walking
.The meter is converted to the usual extended scale meter using the usual 6.2v zener method.
Picture 2 shows the pcb mounted into the transmitter case. Picture 3 shows the completed transmitter.
Im just on with the receiver conversion, need to design and print a new casing for it as the original metal case is not suitable for the 2.4ghz receiver.
Ill post it here when complete.
Here is the STL file for the mounting plate