Hmm. I've seen Biltrite heels before, but never like those and usually, if not always, as replacement heels, so I'm thinking those heels are not original. If you have to ask, I'm guessing that there is no indication inside the shoes. The old school Florsheim grails always have Imperial embroidered on the inner side and printed on the insole--the insole can wear off, but the inner side label is permanent. Do the soles have the five-nail pattern at mid-shoe? Any country of origin indicated?
I have two pairs of Imperials sans v-cleat and without the embroidered inner labels that are still very nice and made in USA (off-shore Florsheims are crap). I believe they have rubber heels, but I'm out of town at the moment and can't recall for sure. Certainly, they don't have heels like that. If they aren't Florsheim, Hanover and Nettleton also made equally nice longwings back in the day.