Here is a before and after
When i bought the new head (the old one had a broken lid and a seized leaking pump) i checked that the mounting footprint was the same and i assumed that the base would be also but it was a bit longer
I considered repositioning it off centre but there was not enough bum clearance or lifting it to clear the chamfer but in the end i decided to take to the liner with a die grinder to make it fit
I am going to seal around the hole but any water that goes down there runs into the bilge so it is probably not critical
I also didn't loop the waste pipe (to try to make it clear easier) but we make sure that the sea cocks are always closed unless we are using it
Regards Don