ahhh sounds like me 2 years ago
you can't really switch clusters with newer chassis' but if you have an 85mph speedo then you can get a 120mph one out of a diff year w123 (you should have a 120mph though)
Also, like Itrain300D said, get the H4 lamps off eBay. MUCH better than sealed beam. When I got mine they were brand new Bosch units so i was happy.
When you go for parts, believe it or not, the dealer is actually a good place to check. Most of the time they have better prices on stuff than Aftermarket (always check Fastlane though, just to be sure)