The SRT-4 is a bad comparison. It is a closed deck block with plenty of meat between the cylinders. I've tuned plenty of 81mm - 85mm setups. There is no reason to go 85mm on a daily driven car. Just giving you some advice on things I have learned over the years. Not from listening to people but actual experience. If you want a responsive setup do an 84mm block, 10:1 compression, DART head and 95mm crank. I made 485whp @ 12lbs on 93 octane and 630whp @ 19lbs on C16 spinning with that setup. Only thing I would add is L19 head studs