Replacing boom blocks

Not sure why I can't find a previous comment online about this, surely someone has wondered before :D.

How do I replace a boom block? Do you saw off the old one and then is it a rivet that locks it on?

I want to upgrade the boom blocks on an old boom from the blue ones to the new black Harken ones. I assume it will come with some form of instructions but wanted to check first.

Easy pease.Drill out old rivet heads,punch out rivets.Put new blocks and hangers in place and use rivit gun to replace.New blocks come with the SS Rivits
Does anyone know what size rivets are used to attach the gooseneck to the lower section of the Laser mast? Same size as the blocks?