Polaroid T-55 data sheet is still available here:

http://www.polaroid.com/service/film.../4_5/55fds.pdf

You want a fine grain film with a similar HD curve.

Of Kodak films presently available, it looks a lot like Tri-X Pan Professional (TXP320). Long toe, long straight line section, no shoulder. Very much like the classic (but discontinued) portrait films like Ektapan and Royal Pan. Or even like Verichrome Pan.

Ilford's Delta 100 is very straight line, no shoulder, but but as much toe.