Looking through my 3 worlds a very brief look:
Phelan - Piman at CalTech had at minimum 70 in a row, looks like it probably ended in the very low 70s as he had 4 non conf loss the season after b2b 35-0 champs.
Narcotico in Tark at Greensboro went 34-1 35-0 and 34-1 but unfortunately for him went it comes to longest streak those 2 loses were in unfortunate positions, but hey he still won B2B2B.