
Mines getting between 45-60+ mpg and is responding well to veggie

Get the coolant changed ASAP as they are known to eat radiators and this may well help stave it off!
Also the purflux filter is a pita and if possible best to replace it with another unit.
Does it have aircon?
For the radio you can update to almost any new radio as it uses ISO connectors

Clean the exhaust off with a steam washer and see how rusty it is and treat if possible as they are big old units!