Hi and welcome to the forum from another old timer!!!
Used to rally a 2300 magnum coupe in the day although only at club level in the north west.
Happy Zedding !!!
Go for the HR 313 for reasons you've already stated.
Its a great car and great engine.
The extra road tax is only 2 tanks of fuel and shouldnt really be an issue when buying this type of car unless you are a real tight ar8e.
Tax is £500 a year which in my opinion is worth every single penny!
The pleasure you get from driving this car is priceless!!
Sounds like the clutch thrust bearing.
I wouldnt worry too much as they are all known to be noisy
You'd have to remove the bellhousing/gearbox to access it which is quite a big job