Compression test only at 90 psi max, timing chain off?

I had a post a few weeks back about not being able to start my car. It is a 340 Duster that I had machine work done, I assembled it with a book to put everything to spec. I just ran a compression test and maxed out at 90 psi on almost all the cylinder. I had 2 that were only about 75. I don't believe this is high enough. It sounds like combustion doesn't happen until a minimum of 90. I did add some oil to each cylinder and tried again, had luck on a few, but still nothing higher than 90.

So next step, could the timing chain off affect the compression? I am going to tear into the front to get at the timing chain and check that. The heads were done at a local machine shop. I installed the rings per instructions and put plenty of oil on them.

I hope I didn't screw something up, but it's not looking good... Hopefully it's only the timing chain. I did install a comp cams XE274 and am using stock pushrods. Could that affect anything?

Any guidance is appreciated for my first build...