Stainless front brake line source?

does anyone sell a "kit" to replace the standard single disc brake lines with braided lines? My bike is a 1981 XS650 completely stock. I'd rather not try to piece together something.

Several ways to "skin that cat"; there is some good discussion here:
https://www.xs650.com/threads/75-front-brake-refurbish.54088/

And.....It appears MikesXS sells an upper line @ 17" long that comes with banjo bolts that claims fitment for upper "standard bars" '77-'84 (????)
https://www.mikesxs.net/yamaha-xs650-stainless-brake-hose-77-84-upper-front.html (I think the lower is 17" also)

Personally, I like to use Russell braided line in the "Renegade" series - as it's black and resembles stock black lines. You can replace upper and lower lines, keeping the union, or run a single line from master cylinder to caliper. That set-up requires new AN3 Banjo fittings (Renegade or Goodridge Ebony). Just measure existing lines and note banjo fitting angle to assemble what ya need. Several sources, one here:
https://www.jpcycles.com/product/245-300/russell-renegade-universal-brake-line

https://www.jpcycles.com/product/243-010/russell-renegade-banjo-fitting

https://www.jpcycles.com/product/241-765/goodridge-ebony-series-banjo-fittings

For any solution, you'll need a supply of 10mm copper washers - found everywhere

You can reuse the stock banjo bolts, or buy new 8mm x 1.25 thread banjo bolts.

I use Russell and Inline Tube but never the molded banjo ends. I always use #3AN female fittings and #3AN male adaptors. Unless the molded banjo fittings are the swivel type they limit the angle of the line fitment. Always try to get the clear coated lines.
https://www.inlinetube.com/products/sh34
https://www.inlinetube.com/products/bn07a
https://www.inlinetube.com/products/bn03a

I use Spiegler lines and am very happy with mine. While the front end I used is not an xs650, sportbiketrackgear sells them for the xs

I use mostly Chinese cheapies from eBay, less than $10. For bars slightly lower than stock, a 90cm long line is perfect. However, most of these eBay lines have the banjos parallel to one another and that doesn't work too well with the stock MC that mounts the line out on the end. You want a line that has the banjos mounted at 90° to one another. But a line with parallel ends if perfect for a MC that mounts the line on the front .....



I've changed both my MC's to slightly smaller ones (11mm and 1/2") from other Yamahas, and they use front mounted lines.

Hel brake lines do make lines for specific bikes. They do have one that fits an XS2 possibly others XS models.
If you do not need certified lines for road worthy certificate you could buy the AN fittings and make it yourself as previously suggested a lot of classic race bikes here run them.