It's gonna be tough to get great low end and mid and at the same time have a top end. One end of the spectrum will be short changed. I'd get an MX port.....that should give you what you want, unless you want more up top at the sacrifice of some down low....then get a dune port.
If you go for more mid and upper, you can get back some of the lost bottom end with timing and compression...however, you didn't say if you wanted to or minded running race fuel.
With more compression and timing, you'll need race fuel....normally.
Also, if you're gonna have it down to the tranny, have your porter weld the stock crank too, for reliability...
cheap, and well worth every cent once you start putting more power out of that motor!!!