Re: 1972 tartan 30
Here are some ideas,
My T 30 has a universal 3 cyl in it, I think the same block as the beta. I think running it prior to purchase is a great idea as you do not know where the bilge oil came from. On mine the oil filter is on the back (port) side of the block and is horizontal. It is impossible to get it off without slopping some oil. I use a plastic bag under it to catch most but not all of the oil. My bilge also had some old oil in it, most likely had been there for years from the old A4. Run it and see what happens.
The rudder is foam encased in FRG, the post has horizontal metal bars welded to it. To the best my knowledge they all leak eventually. If you have not already, have one person hold the rudder while a second moves the tiller. If there is slop check the hinge at the tiller and attachment to the post. If they are secure then the post might be loose in the rudder, a fellow owner found his horizontal supports had rusted off the post in the now saturated foam. He fixed it as a DIY project, not easy. My rudder leaks a bit of water when pulled, has been in the water year round for 40 yrs and is still solid.