Need info on putting a Hemi in my 69 cuda

Welcome aboard Jeff. It sounds like you already have a pretty healthy power plant under that hood. :thumblef: I don't know how much "go" you'd pick up with any of the older hemis compared to your 451, so the 426 would be my choice if going for power. Having said that, you could coax quite a few extra horses out of that 451, and save yourself a lot of headaches doing the installation, for the cost of a hemi. :)