Here's a sister site where the current guardian of 605 is seeking information on certain kit(s). His e-mail address is there. Why not put any advice on here and then tell him of this site. (Hard to believe - that awful RadAlt was fitted as late as '81. Is that right? Proper RadAlts, same as the Trident, were being fitted 15 years earlier.)
http://www.vulcanxm605.20m.com/interior.htm