Proving the internet is a fragmented place not particularly suited to amateur qausi academic research with any comprehensive coverage, I finally complete the full cycle of the history of the CSVT power unit prior to it becoming the RK270 as fitted to the class 56 and 58, and with around 35-75% more power per cylinder than the two 1960s locos in the UK fitted with said beasty, growling power units, the 37 and the 50.
The first two links in this evolutionary tale come from in fact the V8: used in the portugeuse Switcher type locos and the NIR class 101 "thumper" class , where I had heard they were rated up at 1500 hp, but Wiki informs us 1350 the same as the iberian ones. At around the same time, the Aussies had successfully rated the v8 at 1760 hp in the KTM Class 22, which prove to be more reliable than both the Class 50 and the 101s of NIR.
The KTM class 22s were built in the early seventies in Aus' by EE / AEI. The clue here is that they used the CSVT mark III engine. It seems that this engine was not developed in Europe, where the major project was the metric RK instead.
Indeed then the Aussies were pretty keen on EE and developing locos as the power unit technology advanced, seen perfectly with the v 12 going from say the QR class 1270, 1300 (1540 and 1800 hp respc.) up to the 2350 a the same nominal bhp, and there is a quote of taking it to 2550hp ( far short however of the 3300 hp in the class 58) . The RK270 was then first installed in 47 601 at the time, in 1974 thus being built at the same time as the aussie MrkIIIs and probably sharing technology.
The Mrk III engine was the last used in Aus, I believe from EE and its later GEC who by then owned all of EE and subsidiaries including Rustons and those in Aus. It differed from the predecessors in having gear driven cams and a single stack cumulative exhaust route deliverying to a single, very much larger turbo charger. In the 2350 (at their full rating, not the Tasrail down throttelign to 1750) they sound most like the RK215 engines in fact, spluttering a bit and couging rather more than dubbing, but still recognisable as a thrashy v 12 from Rustons, as in fact is the v12 in the class 58 if you listen carefully or see the video from Tinsley depot, which included footage of them running around with their silencers removed.
The mark II is familiar in the class 37 and class 50, being at ratings of 167 bhp / cylinder in the 50 and 37 292 (2000hp experiment) and 145bhp. Meanwhile the aussies did the KTM at 220 bhp per each of her 8 cylinders, and the eventual 2350 at 195 bhp per cyclinder in her v 12. This compares to "47 601 " and the class 56 at 3250 hp overall, as 203 hp, and the 47 901 v 12 er then at the massive 275hp. Jumps of 30- 40 horse power then per cylinder in the early seventies and finally the sky was the limit for rustons and the smooth running v 12.
However now the missing gap in my mind, within the evolution from 10000/100001 , the humble class 08, the 20/40 rating and the UK ratings of the CSVT for traction use. A jump of 40hp per cylinder to the Mrk III and then a while went by before the class 58 came along. I sigh a little sigh of relief