Thank you all very much for your very kind and helpful replies. I've been in touch with Midland Valenta 3D Prints via Facebook and the Lima Mk3 coach end is definitely something which will be included in my IE push-pull conversions. I have four SOs I bought as "spares or repair" which are complete apart from ends and bogies, the latter isn't an issue, as I can either modify the coaches to take altered old Hornby bogies or use the Southern Pride bogie kits with them. The set I'm intending to build will include the unique Cafe/Bar coach, which I intend converting from a Lima Mk3 TGS, but I'm not intending to go down the "straight repaint" route with that one, as it's incorrect to do it that way. As I'm in the UK, I haven't a lot of information to hand about the Mk3 Cafe/Bar.
In addition, I've emailed Studio Scale Models regarding their Mk2 EGV conversion kit and Mk3 push-pull conversion parts/decals. Just waiting a reply to that at the moment.