Hardtop: help with finding setscrew BD20487/3

I’m not finding from any of the leading usuals the hardtop setscrew BD20487/3, which secures the attachment brackets to the hardtop (part# 8 in the top image of the attached file).

Ideally I’d like to find 4 NOS or used original screws – but at least I’d hope to find a correct looking screw. The bottom imagine in the attached file shows a picture of an original screw, which is chromed and slotted (and I believe cheesehead).

(And a relatively minor point: Only one of the usuals lists the 2 washers for that screw. However, it lists both washers with superseded part numbers, and it lists the original chromed “special washer” (part#10) as just a “plain” washer. So I’m wondering whether those washers would be correct and/or fit an correct screw.)

Does anyone know of a parts supplier that carries the correct screw (and washers)?

Assuming not, can someone with an original screw tell me its length, OD and TPI so I can start hunting on line and at hardware stores?

Thanks
E-Type Hardtop – BD20487-3 setscrew for securing attachment brackets to hardtop.pdf (457.9 KB)

It looks like the same screws that attach the center latch for the top - cheese head, chromed. May be a different length or size, I don’t know. You might first determine the thread size of BD.20487/3 and approximate length and go from there.