Is the IO-390 used on any certified aircraft?
If so, then is it used with the exact same prop as you have in your RV?
If you can answer "Yes" to both of those questions, then you have a chance your inspector will assign you a 25 hour test period.
Van's, all of them, are experimental (with the exception of the factory built RV-12's) and having "the IO-390 and Hartzell prop. normal,normal" doesn't cut it because your "normal" is still experimental.
The idea is if you took an engine and prop from a certified aircraft, say you had built an RV-7 and used an engine and prop from a Mooney, then you would probably get the 25 hour test period. However, since there is not an aircraft certified in a non-Experimental category with your engine and prop combination, you are unlikely to get 25 hours.
Besides, 40 hours gives you a lot of time to complete your required tests and get used to the aircraft prior carrying passengers (other than required for a test flight).