will you be connecting the original saab bodywork, outboard of the fuse box, to the rad support area? originally it was connected with the square tubing across the top, just thinking it may be an idea to keep things strong up there if you plan to attach the fenders to that somehow. I know, it was just the inner fender that was bolted to the inner edge of the fender there but on my 57 the inner fender also bolted to the rad support and the lower area of the firewall and helped stiffen and firm things up there between all the parts.
here is a youtube of how one guy aligns the front end, doors to cab, fenders to doors, hood to cab and fenders. it shows some detail and some good viewpoints, things to watch for/consider. maybe you have seen it, maybe you will skip it, maybe it will help somebody lurking on here.
https://www.youtube.com/watch?v=RgUwd9PdWiA