The fuel injection trouble shooting manual is here, about 1/2 way down the page.
http://volvo1800pictures.com/sweden/Volvo_1800_dokumentation_main_page_en.php
If you don't want to drop the coolant level, you can also check the AAV by looking into the top opening of the AAV with a cold engine (Vee should be open) and with a hot engine (Vee should be closed). The primary advantage to the water bath test is that you can watch the Vee to see if it moves smoothly as the water temperature increases.
Interesting that the cylinders with the highest compression test results have the crappiest looking plugs.
My 1971 B20E with less than 6000 km since a rebuild runs 163, 166, 165, 168 psi. The engine was rebuilt with an F head gasket (because the gasket kits don't come with E gaskets). If you have an E engine with an E head gasket the 170 - 175 psi numbers would be more in the money. 130 psi is definitely a problem.
A leak down test will give you more definitive results on engine condition; but, in the absence of having the required equipment, try the dry / wet compression test on the low cylinder. If the 130 psi cylinder cranking pressure increases with a wet test that is a pretty good indication that the rings are worn. Its odd that the plug for the 130 psi cylinder looks so clean. I suppose that it is possible that the oil control ring is working and the compression rings are shot???
#1 and #2 almost look wet from fuel. Try pulling the injectors out of their retainers and then power up the D jet to get the fuel pump to pressurize (don't start the engine). Check for leakage from the injector tips with the fuel system pressurized.