valvetrain troubles

[69mach351]

Hello, I have had trouble starting my engine. I did a compression test and cylinders 1,2, and 7 did not have any compression at all. I even put my hand on the plug holes of those cylinders and there was no sucking or blowing. The engine ran when I bought the car. After a few weeks a pushrod broke so I put new pushrods,lifters and roller rockers, and replaced the intake valve on cylinder 1 because the top of the valve was rounded. Perhaps this has something to do with this problem. ( Whatever caused the pushrod to break caused the piston or cam to break or vise versa??)I don't have experience with this kind of stuff. When I started the engine up it idled at 1500 RPM, which sounds way too high. Soon after this I could not start it again. I am about to check the head gaskets, and the head for cracks. I don't know if a brocken head gasket or cracked head would effect only three pistons ( one on driver side, two on passenger side of engine). I am positive that I did the valve clearance correct ( positive stop valves= tighten down 1 to 1.8 turn). All of the valves go up and down when I crank the engine over. There are no stuck valves. The problem is likely to be in the lifters since I am not sure how to put them in. I assumed that I just had to drop them in. If anyone knows otherwise please tell me. If I can't find anything in the valvetrain I will take out the pistons. However I did put oil on the piston before I did compression to see if it could be the rings. Again I got no compression. If this problem sounds familiar to anyone I would appreciate any help anyone can give. Thank you.