First off,you do NOT want to put a breaker bar with a lever on the crank nut. If you can't get the engine to turn over with all the spark plugs out of it just by using a normal breaker bar and moderate pressure,you need to go back and start over again.
Pull all the plugs and fill all the cylinders with something like Kroil,or a mixture of WD-40 and ATF. Let it sit for a couple of days to allow any that is going to seep past the rings using gravity to do so.
Pull the side plates so you can see which cylinders have closed valves,and then use a auto parts store "valve hold shut" device that is used to hold valves shut while changing springs on OHV engines. I have made them from old spark plugs by knocking out the center and then tapping it so a air hose fitting will screw into it. Anyhow,the idea is to crank your air compressor output up to it's max,and then attach a hose from the air compressor to each cylinder that has the valves closed,one by one. Sometimes this is enough because just one cylinder being stuck can keep the engine from turning over freely.
Sit back and relax until you hear "blub,blub,blub" noises coming from the base (you did remove the oil filler cap,right?) of the first one you hooked the air line too,and then move on to the next one.
Once you have both bleeding air/allowing the Kroil/whatever to bleed down,pour both full again. No such thing as too much lube when freeing a stuck engine.
Hook up your battery and "bump" the starter. I do NOT mean twist the key like you are trying to start it,I mean "bump it". You might be surprised at how often this works.
If it doesn't work,close the rest of the valves and do this to each cylinder until you get them all free and spinning. Do NOT forget to add more Kroil/whatever to each cylinder as you free them up.
Finish off by spinning the engine with the starter for short periods of time until you have pumped up oil pressure on your gauge. Normally,this would be when you would put the spark plugs back in it and start it up,but in your case you would just put them back in and pull the engine. It might even save you some machine shop labor money because an engine that is lubed up and spinning freely is easier to disassemble. At a minimum it will mean fewer parts broken by the machine shop as they force it apart.