JMO, but the fact that coolant has been mixing in for that long, would make it highly likely the oil has not been able to even come close to properly lubricating the cylinder walls, bearings, etc. It would come as no surprise to get a major engine failure once the HG has been repaired. But, OTOH, $200 is not much to roll the dice on and, most importantly, it won't be a big deal to you if something does happen after the repair. So good luck with the work, and who knows, maybe it will last a good deal longer than I'm expecting.