Maxam,
I don't live in the desert but for six months of the year I do live on my ranch in the eastern sierra mountains of California where the humidity is very low and my radials love it. But the other half of the year I live on the mendocino coast where I am careful in keeping all my engines maintained properly or they will show signs of corrosion almost over night.
The 77 is the engine I had over a hundred hours on (that is including 40 hours of bench running just watching and listening to that beautiful engine run) not the 99. I have got the 99 mounted on my Howard DGA-15 and will continue the break-in with it tied to it's work stand. I won't be able to fly it until spring next year at the ranch because our club field on the coast here is too small for a big fast airplane. That 99 almost pulled the bench stand over on the first run. That thing is a beast! It will make the Howard a rocket ship, gonna be exciting for sure.
Tom