Nice project and a good looking airplane! The price seems good, as well. Do you pay import fees as well as taxes and shipping?
What I'm finding with B-TRs is that sometimes the engineering was never really completed or correct. So the modeler does the best he can. The problem isn't building the airframe so much as installing all the systems so that they fit, are accessible, and nothing is Mickey Moused. I've flown several where the shutoffs were sketchy on their best days and where the fuel line was difficult to install and promptly collapsed when you tried to put the model back together. Of course, you can't see that, so when it won't go you have to pull the cowl again to figure it out....
If you read most of the old B-TR plans, they call out for a Berkeley D&E shutoff. Seems like they were designed to avoid the usual installation issues. I've never seen one, but if they did not leak (air), it sure would be nice to have a handful of those rascals.... My current Veco project is now set up with an F2A shutoff. This has a pull-to-trip (opposite of the D&E?) and will likely require a light compression spring on the trip cable to keep it from fouling the bellcrank....
Good luck with your project and show us some pictures along the way!
Divot McSlow