3rd gear is a weak spot.
It's not that the gear is inferior to other bikes... its that the K5 is a animal and 3rd gear is really the first gear that you can hook up and get that power to the ground. While you are in the trans, replace all the snap rings.... Also, measure your shift forks, many are way out of spec. You can't get new ones but you can get yours repaired.
The Wossner is a superior quality rod.
If you are going to mod the K5 better seriously consider it.
If your running stock, the stock rod will work great.
Wiseco pistons went through a long period of low quality.
However, if yours has been up and running for a while then no worries.
Jason at JT Engine Works, operates from my shop
I can tell you this, there are few and far between builders out there that have the eye for detail, the K5 knowledge, and the ability to put it all together in the way that Jason does at any price.
But I say, shop and compare.
Get a quote from all parties..
Get it in writing what they plan on replacing and with what.
Often it's what is not included on a quote that will get you....