i am a sigma owner ( yeah ok ) , any way , my sigma has a carby fed Astron 2 fitted from factory ( its a super saloon model )

i need to know , what is different between the sigma astron 2 and the magna astron 2 .

basically i want to change from the carby to an EFi set up and i was wondering if i could get a head from an Efi-ed magna , modify the manifold to suit the sig , and then dump the whole thing on to my block .

also , is there any difference between the sigma cam and the magna cam in astron 2s ,

and if i blow the engine down the track , will a magna engine go straight in my sig ( seeing that its already an astron 2 ) with out usual mods other than water pump and sump.

any help on this matter would be muchly appreiciated.

no photos avail.
aint got a camera

but the sigmas a RWD car