My opinion: if we're talking low miles/year Panteras, the fuel economy can never justify the cost. And a well sorted out carb, especially if not bought too big, will handle choke, idle, WOT and all that.
But the worst thing about EFI IMO is that you give your power away. I can tune a carb, written a book about it, and there's never many miles distance to someone that can help. My 2009 Cadillac CTS-V with faster than OEM running blower, for that car you can buy HP Tuners sw and it's great and user friendly. But there are so many tables and possibilities and words I've never heard before, I can't do it. I have someone on the web helping out, for $s of course, and he's done a great job tuning my car remotely, but I hate not being able to do it myself.
I would never replace the carb on my classic cars, unless I was a good friend of you and you lived next door
