Interesting how the tension in strings can vary so much. Used to have a MIM Roadworn Jazz and tried it with Rotosound '77 Flats, but they felt like they were going to rip the neck off when they were tuned up to pitch.
Now my '77 P-Bass has Thomastik Infeld flats and they are just perfect (I know it's all subjective). If you can get a hold of TI flats, I cannot recommend them highly enough. Mine have been on for over a year, rehearsed & gigged regularly and still sound awesome...I reckon I've got a couple more years left in them which, in my mind, justifies the slightly pricey purchase price.