Can I test for any oil leaks at home before installing engine?

[WH23G3G]

Is there anyway to test for rear main seal and/or camshaft rear plug oil leaks before I install my 400 engine? I've just got to install the heads and valve components and exteriors then get ready to install the engine/trans combo. I shouldn't have any oil pan leaks or valve cover leaks but I'm concerned about the camshaft plugs on the back and rear main seal. I installed that rear main seal exactly by the instructions but somehow I don't trust it. I put the rubber lip seals correct, smeared them with a little grease since it will be awhile, torqued the cap to 30 ft-lbs. Then I attempted to fill the side cavities with black silicone RTV but I have no idea if it went all the way down to the bottom. Of course it started oozing out of the top and sides, but don't know if it made it all the way to the bottom. Then I dipped the fiber inserts in water and stuck them in the RTV filled cavities. But that seems like it would leak easy. I don't even see what it does. The rear cam plugs I put the teflon thread sealant from the tube on the threads and tightened them as tight as I could. But I don't know if they will leak. 

[Sublime/Sixpack]

You may want to consider building an engine run-in stand. Back in 1992 I had a Pro build a 440 for me, and after I installed it in the car and fired it up it leaked pretty bad, had to redo the rear seal, and replace the pan gaskets, so after that experience I built a stand so I could run my engines before I install them.  Its great to be able to break in the cam and check for leaks and other problems. So much easier to resolve a problem when on the stand then once its in the car.