Big J,
This is my unabashed humble opinion...

I used to hang out at my dads machine shop as a kid...Guess you could say i grew up with a silver wrench in my mouth...

The guys at Gromm Racing Cylinder Heads said something decades ago that I will never forget.
"You can kick performance right in the face with a good port job, if everything does not match to a tee, you may have been better off leaving it stock".
Meaning to me, just because you have $400 running shoes on does not make you a faster runner.....

Let me tell you my odd analysis on porting and polishing.
1). If you will be running RPM's and a camshaft to support it that exceeds the capability of factory condition cylinder heads, you should consider porting.
2). If you have matched every component as far as carburetor, intake, exhaust, camshaft, compression ratio and are looking for that ever so elusive extra 10 HP, then porting may be desirable.
3). If you have a "guru" that can guarantee or money back that you will see a performance gain in RPM and dyno proven HP, I say go for it (but I will need his digits..

)
4). If you are going to build a lake boat that is making 400-500 HP and does everything you want it to do and have no delusions of going 100 MPH...Use the money to fill the cooler and the gas tank.

A camshaft and a carburetor, sometimes exhaust, some compression are your biggest "bang for the buck"...Anything after that the dollar per horsepower gets stupid....
Again, these are just my thoughts shared on an Internet forum and in no way are meant to insult or pursued you in any direction or the other....
GT