about to give up!

I just found out that the 350 in my truck that I just spent some bucks on for a milder cam, edel intake and carb and a whole bunch of other stuff is actualy a 305 target POC engine. Why didn't I check that first??? It will never do what I want it to. Pulling a horse trailer in a 3/4 ton chevy. Anyway, I went down to a 270 crane and new lifters and all and did everything right so I thought. put on new intake and carb and fired it up. It has some valve noise now at all rpms that only goes away when I move timing up to 30 deg or so. It runs better there too. I can't even get close to 12. It won't run. I did verify the timing marks were on on the ballancer. I am sure I got the dots lined up on the gears. I rebuild engines for a living and can't see how I could have messed that up. My only ideas are the cam is machined off center or it has gremlins in it. This thing is totaly gutless. I have rerun the rockers 3 times now and that ain't it. carb is right. spark is there although not when it should be. What else could be causing this kind of gutless running and valve noise from all the valves. Oh oil pressure is 60 all the time and compression is perfect. Oil squirts all the way to the fenders when I run the valves. That ain't the problem. Motor is almost new in it. It just had a worn out carb and way too big cam when I got it. I thought that was the only problem. Any ideas????????????