My 70 R/T SE was tight, I'm 6'2" & 250...if you've gone away from a stock wheel anything that's not flat like the stock wheel is going to eat up space, Also the suggestion to tilt the seat will work well..
In 1976 I bought a 1970 R/T S/E Challenger......guy I worked with had gotten the wife pregnant and she thought they needed a family car.....440 Magnum, 727, 3:55 rear end....every option, including the luggage rack on the trunk lid......In CA back then everything had smog inspections....the smog...