High frequency ballasts for Just Normlicht Proof Top Multi 5000

I want to replace the ballasts in an old Just Normlicht Proof Top Multi 5000. The original ballasts supplied with this unit are 50Hz and it's impossible to get descent iPhone snapshots for clients without ugly banding :-( Before ordering a couple of new ballasts I thought I’d ask if anybody else had made this modification and managed to find ballasts of a similar size so that I don’t have to drill new mount points? The original components are 2x Vossloh Schwabe L 36.334 Model no. 163899 (230v @ 50Hz) -- Martin Orpen Idea Digital Imaging Ltd