We always contacted 35mm film on 4x5 sheets and then cut the film out to the original size and then put the interneg into the 35mm neg holder for magnification.
This is the preferred method.
My suggestion was not to enlarge to 4x5 but rather do a contact interneg . This will indeed give the OP better results .
That would be the superior method if your end goal was a enlarged B&W print, but I suspect the OP might be doing an alternative process that requires contact printing.