In building & testing the single-channel emulation encoders I've used OrangeRx for Futaba, OrangeRx for JR, Frsky DFT, DHT, V8HT, V8FT, V8JT, Fly-Sky, Corona DSSS, Corona FHSS 2way, Hitec HPF-MI, Spektrum DM8... all work just fine, My personal preference by a long way is Frsky, I like the now-obsolete V8 series, but the D series are perfectly ok. Avoid the Spektrum DM9 as it has a weird ppm timing problem, and also anything FASST as they have a minimum channel count and some FASST modules use the PPM pulse width to control things like output power and failsafe mode. I have had a DM9 and a 6EX FASST module working but its a faff, actually my Gem S/C is a DM9. Personally I'd go for Frsky every time.
If you are definitely going ahead, and if you PM me your postal address I will send you FOC a bare PCB which will mount directly to any Futaba-style module via 5 long pins. It suits an 8-pin pic chip, just needs an 8way dip socket, a 78L05 5v regulator, couple of caps & diodes, will save you some wiring and make a neat job of it.
Heres a really old video, actually the PCB is much smaller now but mounts just the same
https://www.youtube.com/watch?v=XM3SQ1briWY
Or you can do it on stripboard, whatever you prefer. There are lots of examples on
http://www.singlechannel.co.uk
All I wanted to do was to encourage you to have a go Mark, do please let us know how you progress.
Cheers
Phil