J19 engine in series 2a 109

Hi all
I'm in the process of fitting a j19 in but looking at gearbox bell housing and j19 flywheel casing
The gearbox has a upstanding rim inside of bolt holes and the
J19 where the studs are they have a small bulge on in side
Does anyone know if both will fit together or does the upstanding rim need grinding away
Has anyone done this,
I have read somewhere they do bolt together with no modification
Any help please Andy

@PenelopeLandrover has a post in series engines forum doing something similar and maybe has the answer to that