HELP Mira Trxx and standard mira


Hi everyone
i hav a bit of a dilemma.
i own a 1992 Mira Trxx and have a problem
i need to know if the block of a standard 3 cyl 660cc mira can perfectly align and fit that one of a mira trxx?????
can any one help me as i have a huge hole where the engine mount is on the base of the engine and need to replace that section of the engine. im hoping a standard 92 mira or some other sort can directly sit under the trxx engine top?
does anyone know if this is possible..
much appreciated
feel free to email me if possible