Greetings from New Zealand.
What a pleasure it is to see such an historic trophy gun restored to its former glory.
My family having once owned an example of this model of field gun (Nr 488, captured by the Warwickshire Yeomanry Regiment at Huj, Palestine, on 8 November 1917), I identify this weapon as a Turkish 75mm modell 1903 Feldkanone L/30, Nr 478, manufactured by Friedrich Krupp AG of Essen in 1907. The markings on the top face of the breech indicate the date of manufacture (ref photograph P9190036) - the Turkish date 1323 (Turkish fiscal calendar) transposes to 1907 (Gregorian calendar), and the gun's number appears as an E, followed by a V and an upside down V (478). You may find the number 478 repeated in Arabic numerals on the front of the small curved section of shield located above the barrel.
My reference for the translation of these markings is an article by J. A. Carter on 'German Manufacturers' Trademarks and Dates on Turkish Bayonets' which appeared in Guns Review Vol 25 No 3 (March 1985), p. 168.
As far as I can tell, the Turkish markings on the rear face of the breech (ref photograph P9190037) which are located between the two Krupp logos (interlocking wheels) repeat the legend 'Friedrich Krupp Aktiengesellschaft, Essen'.
The Turkish number on the lower rear breech face translates as '331'. I do not know the significance of this marking.
Basic data on the Turkish 75mm M'03 L/30 can be found in F. Kosar, A Pocket History of Artillery Light Fieldguns, Ian Allen, London, 1974, p. 121. Kosar notes that Fried Krupp AG delivered 558 of this model to the Turks between 1903 an 1907.
My own trophy gun is now on display in the 'Huj Room' in the Warwickshire Yeomanry Regimental Museum, which is located in the Old Court House, Warwick. I also know of two other Turk 75mm M'03 L'30 trophy guns which remain on public display in the Otago/Southland region here in New Zealand.