Your best bet for new tape is rmg lpr35. It is the closest and best thing around for your machine right now.
You will be better off to get the tape that is designed for you machine.
There is no such thing as a great deal on tape that is not made for your recorder.
Spend the money and get a couple of rolls. You will be glad you did.
If you can find Quantegy 457 that is new then I would go for that also.
Not 456 not 406 get. 457 That is what your machine is setup for and will work the best with. or the lpr35.
The 840 has the right thickness but the wrong bias. Might be worth trying anyway since LPR35 is hard to get.
675 has the right bias but is thicker than the machine was intended to use.