Thanks jacques and barhrecords for your comments and the like.
I'm currently waiting for the official release of 12.03 which I have beta'd. Cliff has again exceeded expectations and as a learn more about how to tweak the amps to sound like the "cleaner" vintage ones, the sound is improving. Having friends with Meazzi echo machines is also great input as we try to replicate the capabilities of those machines. I have discovered faults in the echo timings and the output settings that clearly improve the perceived sound making it closer to the original recorded sound. Reverse engineering from the record works to a degree but knowing the machines used accounts for a major part of getting "that sound".
I'm also adding presets to account for the changing amps from AC15 to ef86 based AC30 and then the AC30TB. I could have used X/Y to change the amps but I have free presets slots so it reduces the complication. All amps were used with various echo machines so the combination add some presets.
Additionally, I'll ensure the presets only use built in amps and cabs (no user cabs). My personal presets will use RedWirez Vox Blues IR using Lawson 47 set at 12 inches from the cone, not near the centre of the speaker. The Shadows recording at Abbey Road Studios, most probably used a Neumann U47 set 12 to 15 inches in front of the cone, not centred. This can be seen of photos taken during recording sessions and backs up various writings made about the equipment used in the studio.
I expect to release a new version later in the month.