More suggestions you say, I definitely agree with other posters on one of the Colchester based locos that worked the Tollesbury light railway, an earlier version of 68619 and also one of the ex-WD industrial locos.
Now that Accurscale have announced a j69 model of the Liverpool st East side pilot, I wonder if Oxford rail could be tempted to do 69614 the West side pilot.
(picture from The Colour of steam The Great Eastern line by RC Riely)
68619 used to travel a bit also as BR took it to exhibitions, open days etc. I have seen a photo of it at Colchester St Botolphs along with a Britannia in the late 50s.