disco 1 to disco 2 conversion

had this disco now for 20 odd years galved it alll that time ago had 3 classic shells on it then started putting dicsco 1 on it as could not source any classics r/r any more im now back at the the same hurdel as cant get any decent dico 1 shells so i noww going to put disco 2 shell on i have just bought a cracker td5 es auto full leather ect 90000 genuine miles on it engine sweet as so going to use the shell for mine
just a thought i have a couple of manual td5 gearboxes so could make it manual has any one done this i mean putting td5 engine and box in to 300 tdi
or am i better sticking to the 300 engine ??thoughts