I had the same urge for a rally style car. With 1:10 cars you get a fair choice of realistic looking rally bodys, but those small tires limits their usability to tarmac and well preperad offroad tracks. There is a small amount of 1:8 rally cars: Kyosho Inferno GT, Thundertiger EB4S2 Rally. They are based on buggy chassis but feature reduced shock travel way. Not ideal for rougher offroad tracks. I decided to convert my old 1:8 Crono buggy to get full buggy offroad capabilities, made custom mounts for a rally body i got off ebay. In my opinion this is the best way to get a rally style car which can also be driven on rougher offroad stuff. The hard part is to get suitable bodys. You can find a fair amount of 1:8 touring/Rally car bodys at this
place. Problem is: they usually are built for onroad use and might have to be reinforced to withstand hard offroad use. Wheelbase might also differ slightly from the one of your buggy chassis: some trimming will be necessary.
This is what i came up with 2 years ago using old stuff i had laying around:
video.