Mark Adams installs an Omex 200 ECU to control the ignition, leaving the 14CUX in place to control the fuelling. Or of course there is the full OMEX 710 option to replace the existing ECU.
Mark Adams has done a couple of OMEX 710s on TVRs, might be worth dropping him a line. I know he rates the OMEX as you can keep the AFM if you choose to do so.
There was iirc a TVR specialist doing OMEX710 install and mapping as a package for RV8 TVRs, I cannot think who though.
there is omex, or emerald, plus a few others but have a chat with Joolz, he can fit and map for you, he is now called Kits and classics and will have a trade stand at Burghley this weekend as well.