Hello mate, fair play on tackling such a big job and I'm enjoying watching your videos. In my late teens and early 20's, I was buying, repairing and selling cars, mostly A series engine Minis and they were a lot simpler to work on back then. It made me smile when you mentioned South Wales Pistons because they machined quite a few blocks and heads for me back in the day. I'm chuffed to hear that they're still in business. All the best and pob lwc. ;)
It'is the first time I see a piston like that on the internet! Nice progress, it sucks though! Anyone buying a mini with engine issues should be ready for a new engine or engine rebuild, you can't be optimistic with french engineering!
Not watched till the end up to now: If you won't try fixing the engine by yourself you will never gain the knowledge. Maybe it's worth to try it. If it fails you gained knowledge anyway. If you win you gain knowledge and have a fixed engine.