I suspect not, although some Class 43 power car were converted to permit operation with Mk 4's back in the period when the ECML▸ was being electrified. Cl43 + 91 power must have been impressive, though sadly I never experienced it despite living on the line at the time.
Not sure the Mk 4 is an improvement, particularly given the bodywork is tapered, so the cabin is more cramped than a Mk 3. Of course, it all depends on the internal fit out, where the GNER▸ inspired refurb is more akin to a rail vehicle than a Ryanair 737.
actually i belive the 43's that were adapted to run with the 91's were only a stopgap due to the late production of the class 82 dvt and mk 4's, im not totally sure that they ever ran with mk'4s.... ive even seen a formation with a 91 and a mk'1 behind it with a 43 trailing