Advice on choosing speaker cables for vintage Altec Model 19 speakers

Well, you haven’t mentioned the length of cables you will need. Some good quality shielded 10 to 12 gauge would do fine. Solid core, not stranded if the installation allows. Don’t over think this. Figure out the length, calculate the resistance and choose the wire. I really doubt your customers have the ear that you do. And certainly not in the environment that you intend on presenting! 

Audioquest in Irvine has bulk spools of in wall rated wire . Let us know when this place opens. I’m going to do a Jazz Kissa pop up in Seattle this Summer… there will be wine and Japanese whiskey 

I have not used model 19's but have used, still use Valencia's, 8309 and currently model 14's. I've tried mid-tier Nordost (red dawn) and found them lean sounding,

16 ga. delund and thought they sounded a little thick. Currently using Kimber 8tc in double runs and seems to have the balance I was looking for. Good luck on your project.

How much length do you need?

Get this audioquest 14 gauge wire, around a hundred and something dollars for 50 feet.

It sounds good. Don't overthink the wire.

https://www.crutchfield.com/p_703X250G/AudioQuest-X2-Speaker-Cable-50-feet-Gray.html

The DJ area is about 143" in width and each Altec is about 30'" in width. The Line Magnetic Tube Amp will be on a shelf behind the DJ. I think 10-12 ft runs should be adequate. We also have a pair of Klipsch Heresys that will sit on the back bar shelves and be fed remotely from the DJ booth. Again not a perfect audio listening environment so there will be compromises. We're hoping to be up and running by April. The space was originally one of my wine bars for eight years and is pretty well build out except for the back bar and DJ area. We've added cocktails in addition to the beer and wine we've had in the past. I have experience at it as I own six wine bars and a prohibition styled speakeasy. Thanks for the advice and all the well wishes.