Is 7 min your marathon pace? Seems like that workout should be easy if that’s the case.
Either way, I do most all my long runs progressive, and build up to longer periods at mp during them. In the beginning i’ll do the last 5k, and later I will do 4x5k and things like that. The real benefit is that you become comfortable at running at mp, but if 90 min of running mp+2 min plus two miles at mp is hurting then I think you may be overreaching.