No top since '83, any suggestions what to try and line up first?

[Toro]

On my '72 Blazer, the previous owner removed the top over 30 years ago. It did not come with a top when I bought it. It has rust in the outer floor edges along the weatherstrip flange, and under the seats but the rocker boxes are solid. I'm ready to do rust repairs, and following all the suggestions here, I need to install the top. It's a double-wall top and after placing it on for the first time, everything is close, but not exactly lined up. The front of the top is sitting good along the top of the windshield frame, and it's centered along the bedsides. However, all the mounting holes for the top down the sides and the rear brackets are about 1/4" or 3/8" off the holes in the Blazer. For it to line up, the top needs to go forward. As I mentioned earlier, it looks like it's in the correct position up front.

So, in general, is there a preferred place to start trying to line everything up? Thanks for any suggestions, I've been worried about this since it's been so long since a top has been on it.