As to the SU carbs. They are a brilliant design let down by a simple flaw.
The throttle shafts wear after about 20k miles and become a variable vacuum leak. You can adjust the fuel mix to compensate and get a decent idle, but then you will run rich the rest of the operating range.
Of course, since the worn throttle shaft never goes back to the EXACT same location, your bodge-adjustments wont really give you a great idle.
If you have no $$$ a better idea is to idle just over 1000 rpm where the shaft air leak becomes less significant in the overall air volume.
As to running an MGB today, it is worth knowing that the method of adjusting the fuel level in the float bowl does not always work. I do not know why. I use an empirical method that observes the level in the jet holder. It has solved several SU issues that were driving me nuts and is now one of the first test I do with a car that is not running right.
Speaking of shaft wear, Frenchy’s advice to adjust timing is spot on. Just be aware that the distributor shaft is probably just as worn as the throttle shafts so do attend to that. Few MGBs show a steady timing mark under a light.
With time as a constant, I see a lot more electrical problems with 50 year old domestic wiring than I do with MGB wiring, Switches can be a problem since relays were not a thing and they tried to pass high current, but no worse than domestic cars of the same age.
An early MGB with a late 4 sync gearbox is a perfect specimen. The early boxes were filled with paper-mache and the non-synch 1st never grown on you to be other than annoying.
Suspension-wise, they are not worth modifying. A full rebuilt front and rear will have amazing results. Most of us judge upgrades against worn out original, but reality is that the factory did a great job except for the front a-arm bushings; use V8 ones.
Performance-wise, I would also stick to factory just so that you have a manual that could get you out of trouble should you ever read it. Once you go to cams and whatnot, all the manual’s advice goes out the window.
If you want to restore one, it is going to cost you 35 grand; if you do the work yourself. That does buy you one hell of a nice Miata of comparable quality. Or buy an already restored one for 15k, that being about the top of the MGB market.
