When I had lifter noise last year on my 86 Syncro (after it was parked for a
week or so), I was advised (by an kindly VW dealer mechanic) to drain off
one quart of oil and replace it with automatic transmission fluid.  I then
drove about 100 miles, drained off all the oil, and changed back to Castrol
20w-50 with a VW filter.  Long prior to the 100 miles, the lifter noise was
gone and has not returned.

Today, I started up my 84 GL which had been sitting for about a week and
heard the telltale lifter clatter.  This time I just drove it.  After about
10 miles, it began to quiet down and soon was back to normal.

I suggest you try either/both of these suggestions prior to getting serious
about doing any mechanical work.

Good luck.

Budd Premack
86 Syncro, 84 GL(for sale soon), 73 Super
Minneapolis, MN (Land of Sky Blue Waters)