Don't waste your time with different sealers. I'll bet you'll have to angle mill your intake .002 to .004 off the high side to get it to seal.
My intake has the same problem leaking oil into the cylinders and I wasted all summer last year trying to seal it. My angles between the heads and intake were about perfect. Talked to Dave Hughes after using lead to check the actual clearance and he said I needed .002 to .003 more crush at the bottom for ideal sealing.
I had it angled milled .003 and I'm picking it up on Monday. Hopefully that fixes it.