PacMan - IV-13 pinouts are not the same as any of the RCA numitrons, so it's not as simple as swapping out tubes. Unless Jürgen included a special feature, i.e. change a few jumpers to change tube types...
Look into it later when the dust is clearing off the crater.
Oh dear, not even the socket layout (DR-2000 vs. IV-13) is different but also the viewing angle (viewing directon IV-13 is the "gap" between pin 9 and 1, on DR-2000 it is pin 3).
No, here you'll need a new board and some resisotor values changed as the DR-2000 has a lower current consuption for the segments (25 instead of 32 mA) as I am powering the tubes with constant current, however, the circuity is able to drive these Numitrons.
The "trick" with the constant current I have used, as the IV-13 have tolerances in their current consuption - and therefore also the brightnes - up to 20 % !!!
And this is visible. But with constant current they all light up with the same brightness.
I think around 149 EUR (without VAT) for electronics, 7 VDC desktop power supply with EU or US or UK mains cord and case.
The tubes can be bought on Ebay. I hold a few sets here on stock, but due to the hight p&p from Russia, tax and warrenty I must give (German laws) I can't sell a set of tubes less than 229 EUR