280GE Clutch Trans Parts
A manual 280GE. That 's rare. I'm sure someone will confirm, but the clutch should be the same as used on the W123 sedans, so you'll probably find alternative suppliers to the MB dealers. Not sure, but the 4-speed and 5-speed manual may have different clutches (?)
http://www.autohausaz.com/mercedes-auto-parts/mercedes-280e-clutch_master_cylinder-replacement.html
http://www.pelicanparts.com/catalog/SuperCat/W123/MBZ_W123_TCLUTC_pg1.htm
Sachs would be OEM.
there are also uprated types:
and aftermarket types:
you have a PM
Yes, but in the US a manual is rare in any car. In europe it's the other way round and certainly from MB the clutch will be available and I have seen other ones on ebay advertised for 4 speed manual.
eg:
However, I'm sure Adrian can sort something for you.
Well there are outfits here in the UK, that will fit a replacement engine for around USD $1,000. However, the key word here is 'replacement' meaning an engine they've taken from a breaker's yard and then badly fitted to your car.
Of any manufacturer, Mercedes has the greatest availability of parts for older vehicles. If your engine needs a rebuild, I think that could be done with a top-end, cylinder-head rebuild for around $1,500 or maybe $3,500 with a re-bore and new pistons, etc.
Incidentally, these are low-compression engines of 9:1, so I would not expect any higher that 9 x 14.7 psi (at sea-level) = 132 psi on a compression test at cranking speed with throttle wide open for full cylinder fill. Your readings are not far off and perhaps just a cylinder-head, valve service would sort any imbalance. There are other tests that can be done to determine whether piston-rings may be an issue.:https://en.wikipedia.org/wiki/Leak-down_tester
$1,500 for a clutch is also a little on the high side. The gearbox probably just requires a new shift-fork or synchro for 4th gear.