This is a safety system, so care required in modifying.

The guy at White Post or other reliner shop may know what fits? Maybe can bore out the originals?

I'd be skeptical about just increasing the bore, as that takes more fluid, so brake response will change. Master and cylinders need to match. So I'd be looking at the master too, if upgrading. If going that far, I'd convert to dual system for reliability.

Agree with LJ, assuming those numbers are right.

I'm not familiar with this model, so no comment if it's easy in or out. But lots of shade tree work was done in the day. I'd consult the shop manual and see what they say about this. Might even be on here. Helped when I pulled mine.

The big straight 8 pan is reported sometimes an issue to get off on the car. If you're cylinder and warpage lucky, honing and re-ringing should be straight forward. Valves might be more difficult without the machines beyond a grind/replace/lap job.
Either way it's a heavy motor to wield around, so need the equipment for a pull.
As they say, won't know til you try, but if it's worse inside, then your stuck. At least it runs now and a few qts oil not much $. Bite off what you can chew.

You can upgrade the generator to one of 40 or 45 amps out, if lacking power. These are common in the late '40-early 50s.
A local electric shop may also be able to rewind yours for more output.
Fan speed is proportional to power draw, so the slower it turns the less amp draw by power of 3. If available in 6V, consider a thermostatic or two/variable speed unit for less draw when not needed.
I assume you've checked your temperature measurement, all the front air deflecting sheet metal is intact, and '39 is not the thermostatic louver year.

Best I could come up with quickly.

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In old timer's parlance, we call that one hour of "exercise"!
God's way of saying you're in big picture land, don't sweat the small stuff.

Some say it's just a part of getting old, I say, we got so much more info stored up there, it just takes a little longer to retrieve it. And I was trained to not remember what you can look up. I could get them all right on "Jeopardy" if they gave me two or three days per clue, especially names. 30 seconds is for young-uns.

I seem to have a similar issue, except I recall I have something, then can't seem to find it. Goes with the territory, not to mention age. At some point a collection out strips the owners ability to recall it and I only have one Packard!

Need a better picture showing the top end and side obscured by the coil and part number. I see some kind of ring holding something on that's not shown.
I suspect it might be easier to get another coil.

ps; found a similar one, that shows the boot for the spark feed wire. With part number can look up more info.

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Something's not coming across clear here.
How did you determine spark was "the" problem?

Was this work done before and you didn't get spark after, or it was not "sparking", so you did all this to fix that, but you haven't completed all the work yet? So won't spark not hooked up? Where you're losing what your question is, you're assuming it's not going to work?

Double check all the ignition connections are tight and in the proper places. Should be a electrical diagram on this site somewhere for that year. Check the voltages to make sure it's hot when key on. Make sure you have the proper parts and they're good. Should be on the Xref list. (Make sure the coil has no internal resistor.) Set the points and distributor to the correct position. #1 on compression.
I prefer to use an instrument to check for spark rather than the touch plug to the head. Some spark, none, or low are different issues. Double check the plug wires are in the proper location per the firing order.
I probably would have replaced the battery cables(suggest you upgrade), if I did this much. 6V doesn't like much resistance and needs larger 00 cables. At minimum, take them off, inspect, clean where they make contact and re-tighten. Wires or connectors corroded or insulation bad, replace.

Other possible sources:
brillman.com

the tractor parts places. They seem to have a deeper inventory and many parts are interchangeable. But you need to know how to specify.interchange.

Local auto electric shop

other solution, put in an electronic ignition set.ie, eliminate the issue.

Just so happens, I was looking up some ignition arts, and
carid.com shows distributor wires. Both sides.