280E valve stem seals

You need a good air compressor... running 100% of time... a leak down adapter so you keep pressure in the cylinder you are working on... to keep the valve closed...

On your head, I believe you need a valve spring compressor to do compress it... a magnet to remove the split retainer...

Oil the stem seal before installing it. A long needle nose with a loop to tap the seal down or similar device to pull and push the seal down without destroying the seal.

I done it on my 380SE... take a while but not too hard at all with proper tool.