This is important because some of the early screws are no longer available.
Buggered screws or modern replacement screws on early Ambassadeurs tell no lies.

I've been using these for a long time.
http://www.natchezss.com/product.cfm?contentID=productDetail&prodID=FP001201
If you don't abuse them, they will last the rest of your life.
The common replaceable tip sets are OK, but "real" screwdrivers in each size is way mo better.
For example, in the smaller sizes you often need a slim shank as well, to access the part. The "tip" system can't do that.

Just don't use cheap, tapered, handyman screwdrivers on fine equipment or you will be sent back to the re-education camps.