Best new drag radial and largest tire size for a 1968 dart in stock wheels

Can't help you with size but best drag radial hands down is M/T been using them for years..
There are several M/T drag radials, Which ones do you prefer? Why those? I bought the ET street SS for the rear as this car will be on street and strip. For the first set, I wanted both capabilities.

To the OP, I have 255/60-15 in my 1973 scamp. room to spare. not sure if I could have gone 275/60-15