My personal experience would have me suggest to any one to go with S/S braided lines all round as the first step. On my own '80 - the S/S lines made all the difference in the world. I have no issues or concerns about my braking power with the stock calipers. I run an inexpensive "Sumo" caliper pad on front. Excellent performance and negligible dust.
It's critical with any brake work to ensure the fluid is clean, to spec. and bled of air 100%.
The stock lines were inappropriate and simply got worse with age.
It's also critical that you apply the brakes correctly. Comments i have seen in the past regarding the stock calipers locking-up, may likely be due to, 1) incorrect balance of application between front and rear, 2) calipers require service due to internal issues, 3) lack of awareness or sudden change in road surface conditions. (speed Too fast for road conditions) The working health of the caliper is essential. If seals and internals prevent smooth proportional application and unhindered return then you're beating a dead horse.
My calipers have never been apart. They have never leaked, seized or failed to perform in any context. luck? Who knows!
Will admit that a multi-puck looks cool.