The 3919840 heads are 1967-69 396/375hp, 2.19/1.72 valves, 106.8 chambers. If the exhaust valve is 1.88 they are 1967-1970 427ci heads. Check them out on ebay. Complete they are selling for $1000-$1500. They are a closed chamber head but would work on a 454 with flat top pistons. You would have to check piston to valve clearance. Compression ratio 8.912.