Ross if you can't find a 261 (not always easy and it may also need rebuilding...some parts may be more costly than for the 235...the 235 engines from 1959 forward to 1962 are nice in that GM made changes to the camshaft in 1959 (a first step toward reducing smog in bumper-to-bumper traffic) and so those produce more torque at lower rpms and have a nice smooth torque band beginning around 1600 rpm and spanning over to around 2800 rpm.
