I don't think your goals in a 440 are far fetched ?
I own an original '69 Charger R/T SE, UN-rebuilt, UN-restored in exceptional original condition, with a factory, and again UN-touched original 440 Magnum in good shape.
I own a Performance Machine Shop and build Drag Engines, so I am NOT easily impressed, but I find the old girl moves along just fine, can boil the hides at will and pleases me when tasked ?
I could rebuild it as easy as childsplay if I wanted to ? but alas ...it is one of "those" a guy don't mess with... because even undoing the factory original Exhaust System still in place might change/damage some thing ?
Nonetheless,
regarding your 'mystery" gremlin Block, as I do this for a living, here are my thoughts.
Please Read....
#1: The Block Oiling Diagram is correct, just the flow arrows are back-asswards in places
#2 440 Mopar Wedges, same as HEMI's like it or not, do employ a version of Main Priority Oiling 60's style, in that the Oil Pump feeds first and foremost the Pass side Lifter Bank, which then directly supplies the Rifled drilled Main/Crank Bearings...... before then crossing Oil Flow equalization over to the Drivers side Lifter Bank at the rear of the Block cross-over, the Drivers side Lifter Bank Oil gallery then dead heading up front by the Dizzy. There is no cross-over of Lifter Bank Oiling at #1 Cam bearing.
The design is Simple, Efficient, and more than Adequate.
Cam bearing Holes on #1, 2, 3 and #5 Cam Bearings, do NOTHING except supply Cam Bearing Lube, except #4 Bearing that has 3 holes, 2 leading UP to feed the heads, and one supply from the Crank, wherein the Cam Journal itself is cross drilled to provide Oil UP through the Block Gallery to the Heads for the Rockers/Shafts as the cam rotates and aligns Oil Flow intermittently to each bank.
Lifters and Cam Lobes Oil strictly from Rod/Crank throw off and limited Oil leakage around the lifter Bore.
#3 One of the problem areas for Engine Block Oiling inspection...... when contemplating rebuilding with older high mileage Blocks, is to pay special attention to an area for inspection at the Lower Lifter Bores for wear, in the area between where the Lifter Oil Gallery intersects the Lifter Bore, and the actual "Bottom" of the bore.
It is an area of approx .375", which can be down to .275" to .300" for the poorer machined Lifter load/wear area on some of the early Blocks.
This small area to inspect for wear is on the outboard side of each Lifter Bore bank, and as the cam rotates clockwise from the front, concentrates Lifter Bore rotational load/wear primarily on the bottom of the drivers side Lifter Bore below the Lifter Oil gallery.
Excessive wear at that point in the Lifter Bore, causes lack of Lifter "rotation" due to Lifter slop during operation, critical to Flat tappet longevity.
I would invite anyone reading this, to go inspect any 383/440 Block Lifter Bores visually themselves, and LOOK for what I am referencing here.... BEFORE contemplating rebuild using Hydraulic Flat Tappets ?
LOOK for the "half moon" wear pattern on the bottom portion of the drivers side Lifter Bank Bores, directly below the Oil gallery to see what I am talking about ?
We don't worry about it on Solid Flat Tappet(order oversize Lifters and re-hone to correct the Bores) or Roller Competition Drag Engines, nonetheless, running anything in the way of a "Hydraulic" lifter ? IMO, just asking for trouble ?
Just my thoughts, no wars wanted.