Indy and ChampCars can be a tight fit for larger guys (both height and girth). 1997 marked a change in safety regulations in that the cockpit area was significantly enlarged. Prior to 1997, the cockpit area was getting smaller as the years went by. Reynards tended to be a bit smaller than the Lola as a general rule.
I am 6'4" and 200 pounds and have to be careful in my choice of cars. I had a couple of "Unser Bumps" added to the inside of the tub in the shoulder area of my 95 just to fit comfortably. Given the ease with which this was done in Indianapolis, it must have been a very common modification. The 96 cars have significantly more room. I can fit easily without any modifications to the tub. The 99 has enough room to have a party with one of your close friends! I was able to build a nice bead seat with a good amount of cushion on both sides of my hips. Oddly enough, my size 13 feet have no problems in any of the pedal boxes. I am a left foot brake guy, however, there is even enough room to right foot brake. The following are interior cockpit measurements for both the 96s and the 99 Lola ChampCars. All these numbers are made with the cockpit inner carbon valences removed.