If I was going to do this I would replace the valve guide oil seals first. This is undoubtably the source of your oil consumption.
I would hold off replacing the cams till this is verified. The reason for this is that the cam stand bolts (half of them) are also head bolts. On the aluminum block motors you stand a risk of taking the threads out either when you remove the bolts or with the retorque. If the bolt won't tighten, the head must come off. So you should find out if the valve guides are resealable first as doing a valve job will cause all this to come apart anyway.
With 191k your valve guides are about worn to the limits and same goes for the chain and upper rails (if original). I would do the whole job at once or at least be prepared to if you can't retorque the bolts.
The two bolts that hold each stand are allen bolts. There are many techniques to remove such bolts and you may not need any but be carefull with your technique. My best tech has to drill the head off one bolt out of 100 even knowing all the tricks. The problem comes from wallowing out the allen hole. If I (personally) did a valve job on a motor that old I would stand a 50/50 chance of ruining at least one bolt (even knowing to be carefull - I do not have his touch or experience - I have seen him work a bolt for a half hour to avoid rounding - to avoid hour(s) of work if he fails)
Probably the best technique as last resort (ruins the bolt) is to have one tech hold a heavy torque on the bolt (considerably more than normal break-away torque) while another tech hits the head in the direction of release with an air impact chisel. The key to this last resort is doing it before you strip the allen hole as you have to be able to exert at least over torque; the impact chisel alone won't get it.
Owner 24 bay BSC
Bosch Master, ASE master L1
26 years MB technician