cam specs 350 M

I've been searching to find out what my cam specs are for a 350 M engine with a stock cam? I want to up grade, but uncertain to what yet. I have several ideas, but to know what I have now to what I should go to is a good place to start. I beleive the lift on 350 cams are basically the same, 260 intake 273 exhaust. I don't know the duration full or 50% lift? Thats the question I guess. My idea is some where around 209/214 duration w/ 424/443 lift,or 218/224 duration w/ 460/488 lift with the heads plained to boost up compression some so I don't loose to much low end torque,with the longer duration cam. So having an idea what I have now might help the oranges to apple theory.:confused:
I beleive I found my answer. According to GMC customer service, they told me that the duration of a 350 m truck cam was 258 intake and 269 exhaust. The lift was a little confusing, for they use some different type of measurement. Displace volumn lift? ! . Comp cams web site in there information section mentions something about this, but doesn't describe it to well. There volumn displacement was .006 which the cam they were taiking about had a .460 lift. Chevy's was .004 volumn lift and the chiltons total carcare book I have shows that the lift on a 350 M was .2600 intake and .2730 exhaust. So inconclusion I would be saft to say that my cam is 258 int. / 269 exh. duation and .260 int. / .273 exh. lift. If this is true, No wonder when I have my plow and sander on it it climbs hills like a turtle.:rolleyes:

Knowledge is a dangerous thing or lack of it