Your height won't be a problem.
Your weight will cause issues as soon as you start riding the bike a bit harder, with luggage or if you take a passenger along. You will have to do some suspension upgrades which will cost in the region of R6k.
If you want a new KLR you will have to buy soon as the bikes currently still available are 2013 models. No more KLR's were imported after those and no more will come.
On the new KLR you will need a set of crash bars right from the start. The plastic bits are easy to break and expensive. A radiator is even more expensive.
Excessive oil consumption was a major issue on some model years (2008 - 2010), the others should be fine unless abused or very high mileage. Or if you go over 120km/h then they all use oil. Fixing an oil burner does not require to re - sleeve the cylinder just an oversize bore, hone & a new piston and a set of rings.
With regards to the doohickey / balancer chain idler lever: It's not negotiable on any model made before or in 2007 KL650A, KL650B Tengai or KL650C.
From the early 2008 models (sold from June 2007 onwards) you still have to sort out the balancer chain idler asap as the mechanism does not take up slack and causes the expensive balancer chain to wear quickly.
At some stage (2010 / 2011?) Kawasaki changed a part of the mechanism to get some tension onto the spring. It kind of works now for 30,000 - 40,000km max.
At the end of the day no mater which KLR you have from the early 600 in 1984 until today: get an Eagle lever & torsion spring fitted.