A common problem when bleeding is getting the caliper pistons in the proper position, close to the disc. Unless the caliper piston moves close, into its proper position, the hand lever will feel spongy. Also, you need to prime the master before it will build pressure. And, as mentioned by others, if the small return port is plugged, you will never have properly working brakes.
It's critical, with an old brake system, to de-crud the calipers on the inside by taking out the piston and descaling everything. Also, replace the brake lines with new. Preferably, teflon/stainless lines.
If all this is done and the system still won't build pressure like it should, then pump the lever and tie it back overnight. This will force the piston to creep forward, toward the disc, and then the lever will firm up.