Bloody hell, who mapped it? It should run less well than normal on 95 RON but no way should it do that damage even if it's mapped on BP ultimate. Unless the ignition timing was advanced too far, or there was some other cause? You haven't recently ramped the boost up or anything?
Did your friend do a wet test? Have you not taken the head off yet?
If it was mine I would rebuild with forged low comp pistons and Arrow rods, full blue-printed lightened and balanced bottom end, gas flowed head, maybe larger exhaust valves, ports matched, steel HG, some animal of a turbo (GT2871R or bigger), intercooler, tubular manifold and custom 3" straight-thru. All running on standalone EMS with traction control and launch control. Being as you have the pennies, that should only set you back £6k or so excluding any labour (apart from mapping and gas flowing). However, I'm not a Vauxhall man.