Splitting the crankcase - usd

I’m trying to split the crankcase without removing the cylinder heads. It’s possible to separate the two parts one inch at the rear and perhaps ½ inch at the front. Seems like something stops further separation. Is it possible to do this or must I remove the heads?
My aim is to change the gearbox.

OK, I think it’s the chain slippers that snags. I’ll try to loosen the slippers and leave the heads and cams in place.

Since no one answers my questions I’ll do it myself :slight_smile:
I had to remove cams and tensioners. The slipper blade in the front snagged a bit but with some wrestling I managed to split the cases even though the rear exhausts where still fitted ( a PITA to remove due to rust etc. Next step is to change the gearbox for a used but good one. The old had a broken fork and a worn shift drum.
The cams are in an excellent shape!! Hooray!! Looks like new (almost) :slight_smile: