Re: Engine Timing..
If the heads are totally reconditioned, then there shouldn't be anything else to check on those. However, fresh heads on a less-than-fresh block can sometimes cause problems. If you've all of a sudden got a super tight top end, leaks in the bottom end become more apparent. Your #4 piston seemed pretty low on compression as compared to the others, but that could have been caused on the top end as well.
For future reference, if you get a low number like that on a cylinder, put a squirt of oil in that cylinder, and retest. If the compression goes up, that means that the rings are shot. If it doesn't, it means that it's most likely a top-end issue.
No way of finding that out though at this point, so no use crying over it.
Check the cylinder walls, and make sure they're all in good shape. Make sure they're nice and clean, and free of rust, nicks, gouges, or--heaven forbid--cracks. While you're at it, take a look at your cam, and make sure there aren't any flat lobes. Now's also a good time to get your intake manifold nice and clean before you put it back in. Get after the ports with some carb cleaner and a wire brush, and get as much of that carbon build-up outta there as you reasonably can.
Make sure the mating surfaces on your block are good and clean before you bolt the heads on. And be sure to use a non-metallic head-gasket when you put it all back together.