Zero chance silicone sealer by itself will work. That's a disaster waiting to happen. Get the intake milled, it's a simple process for any half way decent machine shop
I can 110% tell you for a fact and several thousands of miles. Several years. Unbelievable amount of heat cycles that strictly grey permatex works on its own with zero front or rear gaskets. Been 10 years since I've used one and 20+ engines.