I have a 02 M750Sie(avatar pic) and it also had alot of upgrades.
ohlins steering damp
bar end mirrors
kick stand bypass
adj levers+reservoirs off M900 or SBK's
3k original miles
Its a bad economy right now and CASH TALKS...
If he wont let you take it to a mechanic then walk away there will be other bikes for sale.Also most bike shops do prebuyers inspections for around $150.00.Call around some will even go to the buyers location for you.
I did mine at the Local Duc dealer and it was well worth the piece of mind...