I have an 03 FLSTS with a ridged mounted "B" motor. I put in an S&S 116" kit and have spent a lot of time on the dyno. Last dyno without baffles using Cycle Shack pipes was 141HP and 131 torque. I have since added more compression (12.8:1), solid lifters, and different rockers. I am hoping to be between 150-155HP on the next set of pulls.
My point in mentioning all this is the 6200 is recommended by the factory because they are worried about the chain spinning the counterweights on the case. Not only are the flywheels spinning like crazy at that RPM, but the counterweights are as well. Most importantly, in 2002 (I think) Harley (in its infinite wisdom) decided to go away from a Timkin type bearing on the primary side and went with straight roller bearings. The result is less strength against side thrust. The Engineers at Harley figured it saved a few dollars and maybe was easier to assemble. However, going away from technology that has worked reliably for 50 years was a mistake in my humble opinion.
Going with the motor that I have built (and I recommend this to anyone who plans on doing serious high performance work and wants to take the Twin Cam B motor to above 6200 RPMs) I had a Timkin type bearing installed in the case and changed the oiling back like the earlier models. It takes someone who really knows what they are doing to do this and a few dollors but the peace of mind is well worth it.
The bottom line is, 6200 should be no problem at all. I run mine to 6500 and have pushed 7000 a few times on the dyno but I have the Timkin bearing in it. It does keep on pulling right to the top. These motors like longer stroke (like the EVOs) and compression is a must. Free flowing exhaust and intake will lower the operating temp while adding performance. Add an oil cooler and good oil (I am partial to synthetics) because they run hot due to the piston oilers (these add additional heat to the oil but cool the piston dome 50 degrees).
Last but not least, listen to one person on how to make your bike run. Everybody has their opinion of what works bit it may not work for your combination. It's the right package that works. For the street, I would gladly sacrifice 2-5 HP for more torque. Remember....Torque gets you there and horsepower keeps you there.
Best of luck!!!
John S. 8-)