Internally Balance Cast Crank?

It seems to me that you're trying to re-invent the wheel, but from the position of not knowing what a wheel looks like, nor having the equipment to build it..
I have seen engines that shook badly from idle to cruise-rpm, then smoothed out some at rpm . Eventually, something breaks, and not always in the engine either.
And
then there is my professionally balanced engine, that is smooth as glass, and revs effortlessly to past 7200...... so much so that I had to install a rev-limiter, cuz, as a streeter, I can't both drive and watch the tach at the same time. Mine is a 4-speed, and she whams thru gears pretty rapidly. and, this engine now has over 100,000 miles on it, and is still a strong runner.
I imagine you can build your engine any way that you want to, but when you gotta put new rod-bearings in it every winter, that should send up a redflag, like, right away.
If you don't want to balance the assy, just buy a pre-balanced kit.
Or better yet, pick up the phone and call a vendor for a drop-in with a warranty. Let the guys with the equipment make your parts play nice together.
Then, you can have the pleasure of installing the bolt-ons, knowing the engine is gonna drive for many many years; or at least has the potential to.
BTW-1
my pistons are cast hypers circa 1999, the bushed rods came out of a late 60s 318, the factory flywheel is off a 1970 340, and the harmonic balancer is off a 71 360, which also donated it's block and cast crank. Jus saying. When I sent the parts out for balancing, I never even asked beforehand, what it would cost. It had to be done, so the cost was whatever. I've never been sorry.
BTW-2
The missed-shift event that precipitated the buying/installing of a rev limiter, was when I saw the tach needle crossing the 8000 line, coming down. That was some 18/20 years ago, and the engine never missed a beat. Somewhat ironically, I rebuilt the shifter and have never missed another shift with that shifter.