These are very simple autos compared to modern ones. Probably just a few hundred parts instead of several thousand. There are clubs dedicated to these sort of cars. You can still buy all the parts. A machine shop and an upholstery shop can give you estimates. You did not mention the convertible top. I will guess that $5000 will give you a great but almost 50 year old car.
I love them and have worker on them . send me an e mail tony_crow26@yahoo.com
Any MG from the 1960's that is not a rusted out hulk is worth restoring. There are lots of shops and parts suppliers on the internet. Google MG restoration, perhaps with your zip code because it would be better to use a shop close by.