This is a well-thought out kit. The pieces scale well against drawings for No 20 that I enlarged to full size HO. The wheel base is also right on.
Extra weight is added in the cab, but since the Bachmann split frame remains this is not really needed.
One other good reason to try this kit is the trailing truck suspension. It slides from side to side and will take a 10" curve per the manufacturer. I believe it, based on how far it swings. It provides vertical suspension as well, keeping the drivers in better contact with the track. Not included, but recommended by the manufacturer and shown here are Kato N scale passenger trucks with electrical pickup. I got a used Kato N scale passenger car cheap just for the trucks. B & F Hobby has had them for sale as parts in the past. These will compensate for the limited eletrical pickup due to the short wheel base and lack of tender. The combination of the good running chassis, the rear suspension and trailing truck pickup means this will be a good runner. I'll update this as I complete this kit.
As a disclaimer I have no financial ties or interest to the manufacturer or this kit. I just want to share a good thing. This should be available from any of the three sources in the links section: Trains & Things, Train & Trooper and B & F Hobby.