I suspect the OP just does not like the higher rpms that are required to get the peak power numbers for the already pretty healthy motor...
Just gotta let the engine rev on those grades.. That's like 3500+ rpms and yes, it's loud, but it's gonna be good for up to 5500 rpms if needed too...
If you want low rpms AND power, then diesel, or some other sort of major modification to the induction system will be needed... (ie, blower or turbo setup)
Also, if you are trying to take the grades at 70 mph, then you might need to adjust your expectations as well...
Good luck with whatever you decide!
Mitch