I am wanting to get a film SLR to mostly use for infrared film, and I was wanting suggestions of what the best camera would be for this.
I already have a D70 with several lenses so I want a Nikon.
If all you need is full manual focus and hand metering then all you need is a brick with and F-Mount flange on the front. That would be an F1. However you may like film. Scanned film still beats even the best Nikon DSLR in terms of image quality. Fuly modern film bodies start at under $200.
First off for IR you will NOT be using the camera's internal light meter how ever you may want to shot normal slide film too. I'd get a camera with a good light meter. If you can afford an F5 that would be the ideal. Lacking funds for the F5 hunt down an N90s (or F100) The F5 and N90s were top of the line Pro and consumer film bodies and they use the EXACT same lenses as the current digital bodies (except the DX format lenses will vignette) The F5/6 had the RGB meter like on the new D cameras, the N90 had a good matrix meter
If you want a manual focus body buy one that takes AIS lenses. AIS allowed for both "A" and "S" exposure modes. All AF lenses are also AIS so they will support all exposure modes mechanically.
If you don't need shuter priority exposure mode then any camera that used AI lenses. Going back futther to the F2, F or early niromats you would have to have your AF lenses monified (for about $35 each) to add those old non-AI "ears" for meter coupling
If you want to hand meter and hand focus which you realy have to with IR film. Then any Nikon camera will work but look for a good split prism focus screen.
One interresting camera is the N2020. It was Nikon's first AF body and was a kind of "bridge" it has the old look without LCD screens but was full AF but fully used the older AIS lenses too. These are dirt cheap on the used market. Good ones for maybe $85.00 But my choise would be the Nikon F4, F5, or F6. Something I could not afford when it was new
I still own an F2, N2020 and N90. The latter two would work for you.