Nice little hobby car but the Lucas electricals are notoriously unreliable.  The hold the patent on the short circuit.  Smith's gauges fail constantly.

I'm not an expert but I've worked on those, in fact a friend of mine bought a "restored" TR6 a little while back that I've been helping him with over the last year or so.

It can be a fun toy for summer weekends. Probably the main thing to understand is these are not cars where you can just gas it up, drive it, and otherwise forget about it. Forget the idea of lengthy and infrequent maintenance intervals. If you want a roadster where you can do that a Miata would be the best choice. Owning a car like a TR6 is more of an immersive experience. It requires frequent tinkering and attention. If you get the car be sure to buy a shop manual for it!

A lot will depend on the quality of the restoration. (In my friend's case it was, to be charitable, less than it could have been but fortunately no real deal breakers.) Those cars are notorious rusters, particularly the rear trailing arm attachment points. Check carefully for hidden frame rust that a seller might try to cover up. (Unlike the MGB the TR6 is body on frame construction.)

Engine and drivetrain are pretty robust on these, but they will drip oil - it's a British thing. When these cars were new they'd frequently have drip pans under them in the showroom! The engine is an inline six-cylinder pushrod job equipped with dual Stromberg carbs. You'll need a carb balancing tool for tuneups. In stock form the engine suffers badly from crude 1970s emission controls, especially the later 1973+ models. Of course today there are ways to improve performance.

Most parts are available from specialist suppliers, but quality can be bad. My friend ordered "deluxe" ignition parts from a major British car parts supplier and the points were of such poor quality they could not be used. I wound up just filing the old points and putting them back in for now. (Electronic ignition upgrade later.)

Stock transmission is a 4-speed stick and overdrive is optional. Without overdrive (like my friend's TR6), the engine will be screaming at you at freeway speeds. 5-speed conversions are pretty popular on these cars.

The top is crude, doesn't seal particularly well, and is a bit complex to set up. (It's not a simple pull up job like on a period Fiat 124 Spyder.)

Electrical system - well, best stock up on genuine Lucas smoke for those times when some puffs out from the wiring harness and requires replacement.

http://www.whereisbobl.com/tiger/smoke.html