Working 'out of order' here.. (as usual..lol) On the Czech thing, didn't the country get its name from Czech and Slovokia combined?
I am not at all an international history buff but just vaguely thru Basses and Violins. On the date, I don't know how much Bass building went one during
World War I. Do you? My Martini is labeled and dated 1919 so I am sure some making was going on but that was down in Italy. Between Germany and Russia is where I am wondering as that's where this Bass probably came from.
Ok, questions.. 40 1/4"? Not a problem if that's what you like.
Change the String length? Not always so easy to make it longer. A pitched shim under the Neck pulling it back or re-pitching the lower heel (that's if this is NOT a Blockless Bass) might get you 1/4"-1/2" more. If it is a d-neck and this is a valuable Bass, a longer neck-graft with a similar heel with an Eb stop would get you over 41" in total. Ebony Fingerboard? Sure, why not? It's the modern standard but wasn't 100 years ago!
I don't' know the Bass you are talking about without pictures. Then I can maybe access the condition, value b4 and after repairs/modifications, how much repairs might cost (in my world) and the total value when all is said and done.
Why to buy a specific Bass? Well, it must fit you and your specific needs unless it's an investment purchase and It must not cost more to buy and fix combined than it will be worth afterwards. Also, make sure the work is done correctly and professionally or the so called improvements might actually devalue the Bass.
Pics, measurements and details please?
Personally, I would love to own a nice original old handmade Bohemian Bass and/or a Viennese classic. The real good ones rarely leave home! I doubt the old Vienna Philharmonic or the Czech Republic National Symphony Orchestra used many Italian or English Basses a hundred years ago or more. I don't know much about these orchestras and the history but I do suspect that Eastern European Orchestra most likely played on domestic instruments for the most part.