So I drained the sump again this morning. maybe 1/4 cup. Started it up and sure enough no oil return initially, but built up to steady stream after about a minute. That leads me to believe the oil feed and return system is working as it should.
Took it for a 5 mins run and sure enough, still leaking from what I think is the breather. (Too hot right now to go poking about). Next stage then is to remove timing side cover and have a look at the cork. One thing I am not sure of yet is how can you check camshaft end float with the cover on as advised? That might become obvious when I get inside it, but a bit confused right now.
Thanks for all the help and advice, this is one great forum.
David