There is no problem doing that. Realize that the 'modern' miniature tubes
of the 1950s that were used to make FM tuners are internally identical to
the old tubes from the 1930s.

You use a 6K7 instead of a 6SG7 for instance. Or if you want to go even
older, a 36 I think. A 27 instead of a 6AT6 (triode section).

The lead lengths are longer and might require a bit more care in layout but
it should be okay. Just look at the Hallicrafters S-27 for some ideas.

Bob