The key to remember is the Eddy heads have a way better port and chamber over the old 063/215's to start with.The 1969 396/427 "063" ( I think 215 and another head are same) heads are 100.9 cc Semi open/closed chambers that IIRC Edelbrock copied their 100 cc BBC head to help raise comp. on low comp. 454's, I had a set I used sanding cones to smooth everything but I left chambers alone as PO done something but I did have 1.88/2.19 SS valves & new guides and a good VJ done and the engine really was fun after that, I did buy an Isky piston notch tool to cut the radius on the dish piston valve relief wider for the 2.19 int valve & deeper for the .533 lift cam but ended up $1,100 in iron heads Not including the Isky tool