Low gear set will help, in first it will basically turn your 3.23 rear gear to something closer to 3.65, Yes the gear spread is more but you can compensate for that by shifting the motor at a bit (a couple of 100) higher RPM. Put a good (Street/strip) shift kit in it, just a bit higher line presures will help firm the shifts as well. Might as well put new bands and clutches in it. Higher stall converters with low torque and 3.23's is probably not a good recipie, but the deeper gear set will increase your instantaneous torque alone and your final stays 1:1. Cuda A bodies are fairly light.

Recurving your distributor for a little more initial and less mechanical would probably help your acceleration as well. Switching to a set of bowl ported late model '302 casting number heads (heart shaped chambers) are worth a bunch without having to go into the short block.

With the right parts you can make a 318 perform very well and get very good MPG. Even swapping to the OEM replacement 360 cam (single pattern .410 lift moved up 4-6 degrees) works fantastic in a stock/near stock 318.