you can fit 1000 and 1100 cylinders and heads easily. 996, 749/998/999 will also fit onto the stud spacing.
900/1000/1100 con rods are 130mm long, 6mm longer than all others (except 749r and 1198/1200), the piston pins are 19mm and they are big end located. all 3v/4v rods 996 > are small end located and 20mm pin. same 42mm big end.
one issue you need to look out for with using the longer cranks with cylinders from other engines is how far the pistons come out the bottom of the cylinders at bdc. using a shorter rod to help make it all fit at tdc will make it worse at bdc.