I fitted a petrol eberspacher heater in my wifes 67 a few years ago and it was ace!! You could turn it on, go back in the house, have a brew, return to the car and it was defrosted and toasty warm. Bit dear though but well worth it (about £400) 
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BEER, ITS MORE THAN JUST A BREAKFAST DRINK!!!
67 Egyptian import type 2(playing away)2275cc 164bhp@5660rpm 
97 Golf 2.0Gti(daily)100ish BHP 
08 Vauxhall Vivaro (work)125bhp 
95 Honda Fireblade (fun)130bhp 
63 Bug project (not started)0bhp no engine
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