my manual brake experience

It just sounds like something is wrong with your setup. My son's valiant stops very easily with the big car discs and an aluminum master cyl. The cyl. came off a junk 85 5th ave.

My sweptline has an iron cyl. off a manual disc a body, with a scarebird disc conversion. It too stops really well.

My son's valiant used to be my wife and I's only car for several years. She drove it as much as I did with manual discs. She never once complained about it. If we left the house, we took the valiant.