Remember that there were severe issues of valve guide wear back in FE days and also the old rubber seals get brittle with age and break up into small pieces and block the oil returns plus the oil pump pickup screen. Those seals at first were pretty good but valve guide wear was an issue with all brands/makes of cars up until 10-15 years ago-used to buy valve guides by boxes of 100 and had to have 5 different sizes plus thousands of dollars tooling to machine head, install guide and finish size.

Take the valve covers off and see if there are black rubber pieces lying around or if you have the white Teflon type seal held on by a steel spring band.

Smoke could come from lwakie intake guides into cylinder(plugs should show a little oil residue-----or the exhausts will let oil in that will cause smoke but nothing will show on compression or leakdown test procedure.