I need engine tuning help.

I have a 73 318, unknown mileage, stock heads, LD4B intake, edelbrock performer 600 cfm carb, flowtech headers, 340 cam, 340 air cleaner assembly,323 gears, 275/60/15 tires, stock crap 904 with no converter.

Drives fine no hiccups,sputtering or stalling with normal driving. I did notice before if you have it in gear foot on the brake and blip it then let off it idles low or dies. The car pulls pretty good up top but I feel there is more to be had on the bottom end. It also gets about 10 miles to the gallon.

I have replaced the plugs/wires/cap/rotor very very recently so those are good to go. I also swapped the distributor with one that was in A LOT better shape.

My initial timing is probably around 15-20 btdc. Its hard to tell because the thing only goes to 10. I tried in a bunch of other places and where it is now it runs the best.

I have a kit with a ton of jets and stuff for the carb. I really don't have money to spend on any other parts. I could afford to buy new springs for the distributor if that would help but, not intakes or carburetors. What I have its what I'm using. I also don't want to get a converter as I have a full 4 speed setup I will be swapping in at some point.

Any help is appreciated.