2006 XJ8 L

Bought this recently from my late father in law, one of the last of the MN Vikings Purple People Eaters. My wife was very happy to have it. At 192K miles, I cautioned her that something bad (and quite expensive) was likely to happen shortly. Drove it for a few months before a very slight low coolant issue led to a rapid dump of fluid and overheating. Thought we had it under control until white smoke started to appear out the tailpipe. Bad day. It runs fine, but smokes at start up and again above about 2500 rpm. This car is immaculate otherwise, very well cared for. If it weren't for the sentimental value attached to it by my wife, I'd be tempted to sell it off for parts. Truth be told, I just love driving it. Last of the Living Large Long Wheelbase models. Am thinking I have a blown headgasket, maybe a bad cylinder. A few questions:

1. Is the overhaul advisable? As long as they have to dig that far into it, might as well do an overhaul and have a reconditioned motor.
2. Is there a means to rule out a cracked block or some other cause? I've been told a hydrocarbon test wouldn't rule out a cracked block, and would only confirm the presence of coolant in the combustion gases, which seem obvious.
3. How available are new/salvage motors? Are there other types that fit the same motor mounts?
4. Would you advise a technician somewhere nearby?

Thank you in advance.

 

Plenty of choice if you do a search on your MY engine used which is what I would do since your engine is high mileage.

Nice looking car btw.