Studio flash with DSLR

I am trying to take studio portraits with Nikon DSLR (D200 & D90)

My kit includes three (aging) Bowens Monolite Bronze flash heads.It seems I have to trigger the slave units for the Bowens with the on camera flash. This is no good because it puts the wrong kind of light onto my model.  Can I get a sync lead for DSLR to use with the Bowens heads. These are 30+ years old, still reliable and working well but I am not sure how compatible I can get them with the modern camera. Upgrading is not an option...I own two teenagers in full time education!!  Does anyone have any suggestions please. Wolverhampton is now a digital desert with Jessops gone, and no other outlets where I can go and chat.  Thanks in anticipation for any help!