I'm with everyone else so far, just keep up with the regular oil changes and the chain and guides and you should be fine. My '87 has about 130K on the current engine (first one got killed by a broken chain guide that should have been replaced earler) and runs strong.
Last fall I did the chain, guides, and valve stem seals as you have already concluded that you need and it now is smoke free. I'll add one very inexpensive additional item to your list while you have the valve covers off - cam oilers. They're about $5, take about 30 minutes to install and will ensure a good oil supply to the cam lobes.
Good luck with everything!
'87 560SEL 267K (177K on motor) Blue/Blue
'98 Buick LeSebre 60K (wife's car)
'56 Imperial Sedan 124K
'67 Dodge Monaco 130K (Sold)
'87 Chrysler 5th Ave 245K and going strong (sold)
'73 Plymouth Satillite 175K (sold)
'96 Chrysler LHS 80K (totaled)