A cam really won't help in your case. It's literally the way the 305 is designed on the inside. It's just not meant to be revved, to be beat on to be upgraded. It's not that it's impossible, millions of people have hopped up 305s and been perfectly fine. All the normal hotrod tricks work like cams, headers, aluminum cylinder heads, etc. But when it all comes down to it, they just can't make as much power as a 350. You build a 350 and a 305 with exactly the same parts, the 350 will make more power. The extra 45 cubes add to that too. If you already have the torque converter bought, pick a cam that will accentuate the converter and the torque curve of the engine. I have a little program on my computer that I'm gonna plug in some specs for ya. Gimmie about 10 minutes.