Read his writings from the time: he was conflicted, was pushed into it by his advisors and regretted it almost immediately. That is not "adamantly pro-choice."
Adamanly pro-choice is "Hell yeah I signed it, and I'd do it again!"
Slick Willard is certainly smart enough to know he LIED, and there has been no apology or retraction either.
If Mitt Romney had done the same as Reagan in 1968 and had written passionately about how conflicted he was at the time, I believe, based on observation, that you would call him a liar. In my view, you're doing the same as you accuse Mitt Romney of doing. That's why it is difficult -- extremely so -- for me to take any of your assertions seriously.