360 in a 75 Roadrunner

I have read multiple post regarding a question of more power but my questions are a little different. I have a 1975 Roadrunner with 39000 original miles. It has a 360 with a stock intake and a 600 cfm thermoquad. (I think) it is a TQ though. 3.21 stock gears with a 340 stock automatic cam. It has dual exhaust but I would like to get more 0-30 performance. The car is strong after 30+ but as it being a very heavy car it doesn't have much off the mark performance. So I have thought about different rear end gear but keeping some sanity on highway speeds. It has also the stock heads and so wondering what all of you would do? I have read about different torque converters but I am a little confused on that subject. The car is original and it is only street driven. I know everyone here has a lot knowledge and experience so open to suggestions. Thanks everyone.

More rear gear or more torque are your choices for any reasonable change.
You can get more torque with another converter.
This lets the engine get into it's best RPM range for producing torque on takeoff.

Displacement is another solution, but obviously this takes a lot more money, a bigger motor or both.

I would have to say the biggest change for the least amount of cash is going to be rear gears and the converter would be next.