Sometime in the last 4 years, someone expounded on how to replace the
primary wire from the battery to the starter(and maybe even the
starter to alternator).  Is there a benefit to replacing the black
wire from the ignition to the coil while I'm at it?

I would like to know:
1. What gauge wire is needed(OO, OOO or OOOO gauge?)  Is there an
advantage to using a bigger or smaller wire than factory?
2. Length? If I was guessing, I'd say 10 feet, but Napa's price on
OOO gauge is $7.50 a foot, so excess is a costly item. OOOO is $10/foot.
3. Length and gauge of the wire from starter to alternator and again,
is bigger better?
4. Any tips on soldering the ends on that big a wire without melting
half the insulation off?
5. Hate to even ask what an OEM cable costs!!

And what would an acceptable ohm reading be from the starter terminal
to the battery to test the old cable as it pertains to excessive
resistance.  The napa guy said anything over .3 or .4 ohms and the
wire's resistance is beyond acceptable limits and I should replace
it.  If I add an extension wire to my probes of my cheapo VOM meter,
will that add resistance and give a false reading?

Thanks

DM&FS