Having done literally hundreds of shaved doors over the years, I decided to do something a little different for motors this time. I've used the 35# pull solenoids in the past and they were often marginal on older, heavier doors, and I couldn't justify the expense of the bigger 100# solenoids. So I used a pair of hatch release motors out of late model Camaros. Once you strip off the bracketry you're left with a small but efficient motor with about a 3/4" pull. That amount of pull isn't enough to kick the door mechanism open so I did a cantilever bracket whereby the 3/4" pull is multiplied into about a 1 1/2" pull, which is enough. Here's a diagram...
Cost for the hatch release motors at a wrecking yard should be between $FREE and $25.
Kenneth