I have no model No but a running No of D8129 early BR (I think) in green. It's a heavy beast; body comes off by simply easing it away from the battery boxes and it has pick up on one bogie and driving off the other by a central motor with shaft going to the drive bogie. It actually runs quite slowly and was hoping to get away from rubber tyres and change to Ultrascale wheels but as the layout will be using Peco set track for ease of use to demonstrate to kids will this work or will it foul up / derail on turnouts, etc? I seem to get conflicting info from the net.
If that worked I aimed to do some bodywork detailing as hooks etc are poor mouldings; replace buffers (one missing); replace fan grill with etched version and possibly side vents as ultimately am thinking of adding sound to it after / as converting it to DCC.
The loco shown above is my Class 20, which is a Lima model fitted with Ultrascale wheels and some Craftsman detailing parts. The model runs slowly and smoothly all over Melbridge Dock's PCB trackwork.
Will the Ultrascale wheels work on Peco? Hmmmm.
It might depend on the Peco. Code 75 shouldn't be a problem. Older Code 100 Streamline might be more of an issue. Some of the points had pretty generous clearances in important places to accommodate a wide variety of wheels.
My suggestion would be to try an modern wagon on your track. If it works then I'd expect the loco to work too. I am assuming the track is reasonably well laid. If it isn't the Lima wheels will be more forgiving.
One issue might be haulage - those traction tyres add a lot of grip compared to the steel finescale wheels. This probably wont' be an issue in a shunting yard but if you want to haul great long trains then it can hold you back.
Personally, I'd give it a go. The conversion involves drop-in wheelsets that will be better than the old Lima pizz-cutter wheels. If they cause problems then put the old wheels back in and pop the Ultrascalies on ebay where a finescale modeller will give you most of your money back. Or if Ultrascale are going through a period of supply shortage, you might even make a profit from someone happy to pay a premium!