It's great to hear that you're updating R1, Inferno's greatest strenght was always it's "classic" feel, which is something not encouncered often.
What amazed me was that, first version of R1 (the once for retail FS2) felt even closer to FS2 thanks to model and effects quality. I must say that when I first played INFR1 on retail, the only thing preventing it from feeling completely like a real sequel to FS2 was the fact it didn't had a mainhall. Also, weapon loadout anis looked bad (being made from actual missile models, which were very low quality at that time), but that's all.
I can't wait to see how the upgrade will look.