More carburation is where you want to start. Check out some of the adaptors or manifolds that will accept a small 350cfm carburater or a small progressive 2 barrel like the Weber/Holley.
The exhaust manifold is fine for a stock engine. Long, small tube headers will really help the low rpm torque, but they need to be really long, 35" to 40" of 1 1/5" to 1 5/8" tube. After the headers, it won't make much difference in pipe or size, 2" will work fine for dual pipes, or one 2 1/4" single system. The 250 is a small engine and doesn't move much air in or out!
With out a highly modified head, a bigger cam won't do much except move your power band up the rpm scale to a range you normally don't drive in. All though with your 3.73 gear, alittle more cam wouldn't hurt. Stock cams are good for low rpm torque, under 3000 rpm. You are most likely cruizing above that all ready. Check the rpm range of the cam before buying one. You sure don't want a 4000 to 7000 rpm cam for the street! Joe
