The 216 was pretty consistent in horsepower rating from 1940 to 53, at around 90 HP. The 2nd.-generation 235's from 54-62 had HP ratings from 115 to 135, with the higher power rating due to an increase in compression and a slighty different camshaft profile. The 235 also has noticeably better torque due to the longer stroke crankshaft, resulting in less need to downshift, but not a great deal of top-end speed difference. The carb swap will let you run more RPM at full throttle, but I don't think you'll see a lot of change in the low-RPM to midrange performance. If you decide to swap carbs, use the vacuum gauge to get the idle mixture adjusted correctly. It won't make any difference in off-idle performance, but it will make it run smoother at low speed.
Jerry
