You'll get a pretty good idea how well any kits is likely to go together from assembling the chassis. On that bassis this model locomotive won't be sophisticated but it will work.
Jigging the model up, the frame spacers fitted very nicely with none of the fiddling to enlarge the slots that I've found elsewhere. The bearing holes needed just a touch of reaming out. In fact the worst job involved the bearing themselves which had to be opened to accept the axles. Holding these was a pain - I resorted to the chuck on an electric screwdriver as the metal spun around when held any other was and reamed.
The locating pins on the jig (A Hobby Holidays model) were set using a digital vernier as the end pins are too fat for the holes in the con rods. Chatting to the makers last weekend, it seems that my tool has the pins for Gibson or Sharman cranks pins whereas I use Romford versions which are thinner.