Wanted - Malcolm Mitchell Grange (or motion suitable for a Grange)

[B661Sutton]

Hello all,
The granges are one of my favourite classes of locomotive and I'd like to make one suitable for P4. My main plan was to simply build the Malcolm Mitchell kit for the Grange as I've heard many excellent things about that range of kits. Unfortunately, they're no longer available new (to my knowledge at least) and I haven't seen one second-hand on eBay yet. So, I thought of a backup plan. Inspired by one or two conversions I've seen, I thought of converting a Hornby Grange. I can get a replacement set of wheelsets from Alan Gibson or Ultrascale but, if I do that, I want to replace the original Hornby motion. I know Brassmasters do replacement coupling and connecting rods, but I'm yet to find a good enough replacement set of slide bars and crossheads. The original Hornby slide bars are too skimpy and are ripe for replacement so I'd like to get some better replacements.
Would anyone be able to help? Thanks in advance.

[Captain Kernow]

Have you thought of the Comet kit? - https://www.wizardmodels.ltd/shop/locomotive/lcp60/