I think Diafine, as that is what I had at the time. I now also have HC-110 and TMax, the latter mostly because it gets the higher speeds for TMZ and Delta3200.
Back around 1973 I used that film a lot, processed in Rodinal 1:100, 22-25 minutes @ 20°C, 1 minute agitation @ 5 secs each. Fog levels were always high, even with fresh film, but the grain and soft tonal gradation was unique and is something I do miss these days.
Bear in mind that the true ISO speed of that film, when brand new and in-date was only about 800, tops. Like the true speed of Kodak T-Max P '3200' is really only 800 ISO. After 30 years out-of-date, you'll be lucky if it shoots well at 400 E.I. A better alternative to Rodinal might be HC-110 at dilution C or above. Whatever developer you use, you can expect a massively high fog level. Sandwiching a grain screen with your neg in the enlarger will get you a similar effect. Or maybe Ilford Delta 3200 given a 'compensating' development.