Oh yes... its possible. Fridge would probably tell you it's easy, but then I ain't as clever as him!
Whip off the carb intel manifold, bolt on the EFI manifold and flem chamber and all the 'lectrical buggins that goes with it and job done. You then just need to wire it up!
This is where the fun starts, but if you can get the loom with the injection gear, then AFAIK all you do is give it some power.
The only thing I can think of is that the heads on EFI motors have a small cut out on the inlet port where the injectors fit. It's only a teeezy weenzy half moon shape, but it has to be in the right place obviously! I've heard that some people have just taken a file to the heads to make the injectors fit.
Oh... and the other thing, you'll need a high pressure fuel pump instead of them facet pumps that bolt on the rear outrigger.
Errrr..... think that it tho.
Oh... and the benefits... slightly better fuel economy, more power, if you go Megasquirt instead of Lucas ECU, then you can set the fuel map as you want it too. I've gone Megasquirt simply 'cos I like all the guages that get displayed on the laptop screen... Well bling! B)