Okay, well the one posted is an IBM-7020 (screw down cap, apparently). Mine is an IBM-7008 (clip down cap). Pertronix lists a different part number for both, so I may be out of luck moving my existing conversion kit over to the NOS distributor listed above.
However, if one is shopping for a new distributor this is a great deal.
$65.00 - NOS Prestolite listed above
$80.00 - Pertronix conversion kit (eBay)
$20.00 - New cap (Sierra 18-5352)
$165.00 - Total
That's about $75 less than a new Pertronix electronic distributor so a substantial savings. Thanks!
EDIT: In the even that anyone in my position finds this thread in the future, I just stumbled upon this post.
"The difference between the screw-down and clip-down caps is the shape of the grommet hole where the wires come out of the distributor body. I was told the kits are otherwise identical and that you could use Silicone sealant to fill the grommet voids, if any, when using the kit made for the opposite distributor. There is no change over the years or between cap types, in terms of the other mechanical dimensions of the guts of the distributors - except, because of cap clearance changes, the rotor shapes are different but kit installation does not change that."