the tall deck dose not have a raised cam timing set is the same as stock gm short deck 396 to 454 the only thing that is not the same the deck so with the tall deck you can put more in stroke and use a longer rod as how much stroke on this 427 tall deck with small bores i would not go more that 4 1/2 you can with a bow tie block get 572 with 4 1/2 bore 4 1/2 stroke or 4.600 with a 4.750 stoke i f you use steel rods and i would .080 so nothing hits and if you go 4 1/2 stroke the oil pan milodon makes are nice and the pan they make for the 4 1/4 will work with steel rod s on the 4 1/2 do not get nuts cut out the bottom of the block do not leave any shape spots on the bores