It my opinion only that most amateur photographers make a mistake in concentrating funds on equipment new or used, before their particular problem is defined. E.g., are you unhappy with the way your prints are coming out? Are you changing your approach? Or do you merely wish to modernize? You must answer these questions first then decide on a solution. I believe that expending funds for replacement purposes is unsound unless the item replaced is in failure.
As others have mentioned previously, more details would help better define advice from those here at APUG who are cognizant of these matters. Sorry, I ainít one. My most modern equipment is a circa 1973, 150mm Symmar-S for my circa 1945 Speed Graphic. Yes the Grandkids are pushing me kicking and screaming into the Millennium. Signed: Dino.