http://www.powerhousercperformance.com
Mark responds quickly, and is honest with his opinions about your engine and needs (ie: won't try to over-sell you)
I've seen his work on a buddy's 8.0, and i always considered mine to be well tuned... my friend's just out-pulled me at every rev range, and picked up some higher top end as well.
I'll be sending him a motor as soon as "fun" funds allow.
There are plenty of other places to send your motor - some cheaper, some more expensive... i'm going with mark b/c i've seen his work in action. If you have anyone local from the forums who's had it done by someone else - see if you can hang out and get to see it. If you're handy with a dremel - you can do it yourself.
I'm not - and wouldn't risk a new motor trying to learn.. but i might pick up an old motor and try it.