New hydraulic lifters are fine, look at performance cars or seat supa copas for example, or even race bikes revving to silly rpm. All have hydraulic lifters. This head is a 1992 MK2 golf head though and back then the lifters were 21 year old tech and not so good. I was hoping I could fit a modern hydraulic lifter but I can't after much investigation.
So this is what you have to do with top hats. It's a PAIN with a capital P
Measure all gaps and write them down next to each valave number on a bit of paper
Remove cams
Take out buckets
Take out top hat shims and put them next to buckets in line
Measure each top hat shim
Work out the difference between the feeler gauge figure and what you need and the top hat thickness
Get the top hats ground down what you need to make the gap correct
Refit them all
Refit cams
Measure all gaps and write down the new figure, most will be nearly there now if you got your first measurements right
Remove cams
Remove buckets
Remove top hats
Get them ground again at your local friendly grinders the small amount they are still out
Refit top hats
Refit buckets
Refit cams
And about 8 hours later with aching back hope like hell they are all spot on
otherwise it's all out again and much cussing and more achy back