Plenty easy to "leak test" the heads without a vacuum table. Pour alcohol (or other "thin" liquid) into the ports while the heads are on their side. Fill the port to "above" the valve and watch the chamber side for leaks. If the valve leaks ANYTHING, it isn't sealing 100%, but that's not a big deal if it only "weeps". New springs could fix that.
Also, it may be a good time to LOOK at the valve jpb and see if the seats were done by the head maker or the machine shop that did the build. Mostly, the latter is preferable, IF it's from a forward-looking modern shop. Lapping a "weeping" valve can clear up any leak, too.