If the engine is being rebuilt then the head will be inspected, skimmed + pressure tested before anything so you wouldn't be down 4k, it would be however much they charge to strip the top end down. It would be immediately obvious if there was any substantial damage.As to fixing the L200, the mechanic is saying that getting a reliable replacement engine is always a gamble. I could spend £4k on a new piston set and re-bore, but there could turn out to be cylinder head or valve damage so that would be £4k wasted. The bodywork needs about £2k of work to tidy it up, so it's bordering on uneconomical. He reckons it's worth £2.5k as it is and I'm already down £1.1k for a turbo refurb and refit, which was ultimately unsuccessful. Hard to know what to do....
I'd probably take a punt on a second hand motor from a reputable source. There will be a number of written off l200's out there which the engines were perfect in. It sounds like your garage don't wanna do the work if I'm honest or wants a cheap pick up to resell. An Engine swap won't take long at all in that.
