I have a 74 2.0 all stock. Brakes are mushy and I can't get them to lock up. New pads, caliper inspection and bleed has done little. I would appreciate upgrade advice that does not require significant modification. Would a new 17mm cylinder help?

Sounds like there's still air in the system. Check the proportioning valve in the engine compartment. I've heard it can trap air even when bleeding.

Were you doing pressure bleed, pump-brakes bleed, or vacuum bleed?

New rubber lines?

Lines bled by two different mechanics. Will ask how. I have heard that valve can be an issue