There is a decent modern Indycar body made by Mcallister and I believe a Japanese company may have made a highly detailed one as well. I think the main body difference that the modern Indycar body has almost enclosed rear wheels with wider wings and the F1 car is still fully "open" wheeled. Personally, I love Indycar racing but the latest aero package has an identity problem.
You're not crazy...in the 90's Tamiya had a nice Indy car chassis (f103L) with a Lola body and authentic liveries.