If it's a smooth track. I would go for 70WT front and 60 rear.
Bumpy track 50 or 60 front and 40/45 rear.
For Losi go 5 or 10WT less then those above.
Hope this helps.
If you have the time to test. Don't change any of your other set up details on the car and concentrate on rear oil first, then front.
Look for the way your car handles the bumps the track has to find what you need.
So enjoying building cars I sometimes forget to save some "man-time" to race them!?