I endorse this. 100%. Have done it more times than I can remember. Most are still around thriving.Mick is absolutely right, old silvers have almost no ability to control decay. We have many around here and most have been topped at some time in the past. They all have massive amounts of decay. Yet there they are, year after year, storm after storm, with trees around them in much better condition failing.
If the situation allows, I am inclined to leave old trees because the benefits they provide are substantial. If you want to prune it, it has a lot to work with and not much in the way of targets, I'd say go for it. But don't just re-top it, reduce it to smaller laterals growing in the proper direction and leave any interior growth you can.












