I don't know the measurements of the k-line's height, but thats all we need to calculate a grade ° or % , the units to represent grade. Ideally you want to be at 2.5%, but stock measurements might be 4.5%. You need more tressels and track to lower it, and you may need more tressels for supporting larger trains.
The variables to model RRs are vast.
Spacing depends on track type, done so you land them under or very near the joints. Different track means different lengths. If you run support under the rails, Masonite, wood, etc. you can go further without one. So...8-12" average. They don't even have the same twist or joint resistance within brands let alone across them.
Train type... a light loco weighs about a pound, others weigh like 8 pounds. I you run only 8 pounders or more, you might want to be closer together than that and have two extra in curves.
Do you have a photo, table measurements, track type? Is it simple to describe?
That info could help you create a track plan with the help of some software.
If you run windows, there are some free trail-softwares online to aid you. Apple and I think you have one or two options, with a cost... and less help here simply because not as many folk use it.
Limited to 50 screen items in free ones. These combined with help from folks here can give you a good idea what you'll end up with. I liked Anyrail and loved SCARM. Though the learning curve is a bit steeper, the extra features in scarm are worth it. They contain lots of model scales and brands... but I'd guess scarm would have the k-line if anyone did. (you can still estimate with another brand, but when you use the exact type, it is very accurate.) It's fun once you catch on. Threads for help are abundant. Once you finish building, it's still useful for scenery changes, track changes, etc.
Some searching here for old threads will give you a better clue, but either RMT track is a continuation, or very similar to Kline. Vintage Lionel Super O originated the look. The dark rail came from GarGraves. A well know advicate of S.O. track has been offering some good deals on SO loops in the for sale section here.
The more WE know, the more advice we can offer. You aren't troubleing anyone with detail 
If you haven't bought track yet I highly suggest reading up on GarGraves, Ross, and other track's pro&cons before you buy. (nothing wrong with K-line, but ask yourself how these companies compete for 60+ years on track and turnouts alone.... good stuff )
On the other end of the spectrum, Menard's online... their tubular track should be considered. Hefty, & cheap.
