Copper swarf doesn't sound good, has it got a new rad? Sounds like it wasn't flushed through before & after fitting. Wonder if it's killed the water pump? heaters only getting hot when revving ain't normal either.
Is there anyway you can take it back & get your money back as it's basically not fit for purpose. If it's had a new head etc is there any warranty with that work? Did they fix the cause of the head going in the first place? was it done properly?
If you're relying on an unmodified temp gauge to tell you anything useful, forget it, by the time it moves it's too late, it's damped down so it doesn't scare people. either fit a Mason alarm which resensitizes it -
http://www.townace.plus.com/ie/ietemga2.htm or go for the modification outlined in the coolant alarms factsheet.
If you're prepared to spend the money on it, I'd get it to Ian Taylor, but if it were me I'd be knocking on the sellers door
I know this doesn't help you, but to any potential new owners looking to buy a bongo, walk away if it's "just had a new head" or any simimlar work, unless it's had at least 6 months tried & tested or cast iron warranties that will sort any issues, too many times this happens

Quick bodge job to get it sold on, then a load of grief for the new owner.
You can't polish a turd - but you can roll it in glitter.