As with most cars of that era RUST will be your biggest issue. Make sure you poke an prod everywhere as a cheap car can turn into a big money pit as soon as the paint is removed
If it is a 1976 build year then it should have the 1500cc engine - perhaps with the higher compression head .... which might be a problem with the low octane unleaded fuel more common in the US. They were never exactly fire breathing monsters so don't expect 'sports car' performance but most later cars handled reasonably well - early models had a tendency to "tuck in" at the rear when pushed too hard hrough corners, which is a tendency that can be reduced with aftermarket modifications to the rear suspension. As mentioned, chassis (I THINK they're chassis based not monocoque) and/or body rust are the biggest concern - the engine is fairly robust. Spare parts availability remains quite good - in this country, at least - with a couple of specialist suppliers offering new, used and repro. stuff. Let me know if you want more information. My brother had one for a number of years back in the late seventies and he loved it. 600USD sounds like it could be a very good deal.
My father had one and I also helped a mate in the Royal Air Force with his restoration I can confirm that they have a chassis with the bodywork attached to it Very simple to work on I would love to find one for myself
I met a man once who was bringing mgbs back to the UK from California in good condition as it was a dry bit of America, they did have sand and dead scorpion in them but no rust
Wheeler Dealers tv programme on Discovery UK tv channel did a resto of a Spitfire a few years ago. Turned out quite nice!
I had one....and after lots of trouble with the engine and this tricky SU-carburators I built in a 1.2 Liter Opel Kadett engine....this works perfekt!
I’m the GM of Motorcars Ltd, an independent repair shop in Houston, Tx. We specialize in Classic British cars, Rovers, and contemporary JLR vehicles. If this car has been parked for an extended period of time, you can count on brake and clutch hydraulics, including calipers. You hadn’t said what year it was made, and it really doesn’t matter much. Tires are likely aged out (so think 5, not 4). If it hasn’t yet been converted to electronic ignition, you want to consider that, as they’re a lot easier to live with. If you aren’t capable or don’t have the time to do the repairs yourself, the labor will eat you up at a shop. My rate is $129.50/hour. We don’t do paint or body work - only mechanical and electrical restoration and repairs. I don’t know anything about the car you’re considering. It may be in decent shape, but for $600, maybe not, or maybe someone just wants to move it real bad. Do a compression test. Wet and dry. If it hasn’t been turned in a while it may have dry cylinders and you’ll want to know before you try to turn it. I always have a shop full of old Triumphs, MGs, Jaguar, Austin Healey, Morgan, etc. (Very few Lotus, no Rolls or Bentley, or Italian) Most at least run when they arrive. Some won’t, needing carb work. VERY FEW GET OUT OF THE SHOP SPENDING UNDER $3000, while many are $5000 or more. Sentiments get expensive. Consider the condition this car is in, then consider what you could buy a good running car for - same make and model. Try BringATrailer.com and search for your car, and see what they’ve sold for. Look at Hemmings.com and see what they go for. Think about the motorcycles and motor clothes and other things you could do with that kind of money.
This guy built an MG not the same I know but similar he bought a scrapper and rebuilt it completely. My point is, when he was finish he totalled his bills, 60,000 Pounds. https://www.markevans.co.uk/television/an-mg-is-born/
My advice is get into your car and drive away as fast as you can. I have a good friend that has been tinkering away with a Spit he imported from UK, while he was living there. 10 years and still not a driver. And the "super" versions make upwards of 75hp...