If you can set and store a white balance in the camera, you will get images without any red cast. Many of the newer cameras do not permit a WB to be set due to the long exposure, so you may not be able to set a WB and therefore may have a red cast in RAW images.
The D70 is very good for IR. The question you will wrestle with is putting $250 into converting an older body worth just $200. You might be better to sell the D70 and pick up a D200 for conversion. It's a little more expensive but a newer body and handles IR nicely. Either camera would be a very good choice.
The D7000 is more likely to have issues with a custom WB. Lifepixel has been telling me it won't work. Since you have RAW images, you can choose a monochrome picture control for the camera and get an idea of what it might look like with a proper white balance. But it won't be exactly the same since a WB would turn the red areas white while B&W might make them gray.
Take a look at the Lifepixel site for some examples of different conversions and how they look straight from the camera and white balanced. Keep in mind you can always use a moderate conversion like 720nm and then add a stronger opaque filter if needed.
One approach with newer cameras is to simply remove the UV and IR blocking of the high pass filter (referred to as "full spectrum" conversion). That means the camera can be used conventionally or with filters for IR and UV. Of course, the filters are opaque and you still have to deal with the different focus of IR and UV. But Live View makes that a non-issue.