if going from a carb engine to a more modern version ,one with a ecu ,is it best to retain donor one or go with megajolt etc and how easy is this to do
cheers
richard

You are pretty certainly going to need to fit a new ECU. Most installations junk the standard fueling and exhaust systems and fit a pair of carbs or throttle bodies (for fuel injection), and a tubular exhaust, so you will need an ECU to control whatever you are fitting - ignition only if going carbs, or ignition and fueling if fitting fuel injection.

So what engine are you looking at??

the manta has done its big ends (again ) so thinking more to this problem ,so wanting to upgrade but as sensibly as poss hoping to try keep box etc