I have converted 9 to 2 rail so far. I have found that Athearn wheelsets, or IM metal wheelsets will fit into the lionel truck and thus preserve the use of that gorgeous PRR sideframe. The axles fit a little loosely using the above, but I have a bunch in my parts box, so I use them. NWSL probably makes a slightly longer axle version that would give a tighter fit if desired.
As for height, I think the car body is pretty good, it just sits too high on the bolsters and trucks. I have not tried to lower them. It looks like more of a project than I want to tackle at the moment. I have none of the brass ones, so these do not look out of place as is.
With just replacing the wheels and mounting the Kadees using the included thick shim, the couplers come out at the right height. If you could lower the car the thickness of the shim, it might be close to corret height, and you could mount the coupler directly to the body without the shim. The shim is about 1/8 inch maybe a little less, or 6 scale inches.
I like these a lot of the price. The body detail is as good as the Atlas USRA in my opinion, and provided a different body for the coal trains. I would like to find a set of the M1A ones also to get more numbers.
I just purchased the 2 latest ball keystone sets from Charles Ro and the price was 159.95 I think. It was just under 160. Shipping was 10 one or 2 sets or whatever.