I dont like running the throttle cable through a tube. It gets jammed up with mud & debris. I always weld eyelets along my frame & run the cable through them. Usually 3 is all I need to route the cable. I have done this for almost 20 years and never had a failure yet. This method leaves the cable exposed & as long as the eyelets are placed in the spots you need to redirect the cable there is nothing to gum things up.
I always used the eyelets you bolt in since they have no sharp edges.

You can bolt them in but I like to weld them to keep em in place. I usually run wire rope from Lowes since its cheap. Most Lowes sell a ferrule that you loop the cable & slide both ends through & crimp it which is perfect for the throttle pedal end.

Total cost including eyelets is about 10 bucks. I usually run 1/16th which is overkill but lasts forever. Make up a second cable & keep it in your tool box. Youll never need it but its cheap insurance. Use a length of 3/8" brake tubing to pass the cable through your fan shroud. usually 4 inches is plenty. Just remember to avoid sharp edges so the cable doesnt wear on it.
If you are going to run a clutch cable use a stock VW cable & a cable shortener that buggy shops carry. I use the stock Bowden tube to redirect the cable at the trans.