241 Hemi

They came out in 53, jumped to 270 cubes in 55 or 56 and jumped again to 315 and 325 in 57/58. Bob Walker at http://www.hothemiheads.com is the go to guy on early Hemi's. I've used a lot of his stuff on my 392 Hemi engine rebuild (but no personal experience with the 241)