Oil burn cloud on engine deceleration

The intake valve stem seals are the ones that really matter anyway because they have vacuum pulling on them when the engine is running; the exhaust ports have positive pressure so it's much less likely for oil to get pulled down past the guides. All the umbrella-type seals do is deflect oil from splashing straight onto the valve stem, just like an umbrella lol.

If the old seals still have some squishi-ness to them they're probably OK to reuse on the exhausts. When I did the seals on my old 318 they crumbled apart like some cheap hard plastic. Take a close look at all the intake seals you pull off too, might be able to spot a "smoking gun" for your issues.