Not withstanding the fact that you have these new tyres, I would be considering using 185/65/15 or even the standard 165/80/15 tyres on the Lagunas. Shouldn't need spacers with at least the 165's. Modern rubber gives grip and driving feel that wasn't dreamed of back in the day. Unless you're doing hard running track days and need the ultimate grip, a PV will handle better and feel much nicer to drive on the narrower tyres. The front suspension is primitive at best and doesn't work any better with bigger and heavier wheel/tyre combinations. Yes the suspension can be beefed up, and that is fine for the track, but not for touring. Just saying........