Apologies for posting this again but I posted it as part of a previous
post and only got answers to my first part. I'm doing the work in the
morning so hopefully there is someone out there who might be able to
help but then it is friday night!....

I'm replacing the rim lock and putting in a new mortice lock in an
original timber Victorian front door. The door doesnt fit very well but
we need to get new locks on ASAP. I've sorted out the mortice lock
question but need to work out what i am doing with the rim lock.

Currently there is a shabby looking night latch and a larger rebate
around the edge of the latch indiactng a previous larger rim lock of
some description.

I'm planning to install the big fat Yale deadlocking rim lock and I'm
wondering whehter it would be best to replace the existing lock and
work with the mess that's presumably been made of the door over the
years in that area or just cut my losses, go 30cm further up the door
and install it totally from fresh. any pros and cons in terms of door
weakness and considerations because of it's ill fitting??