Not all #5 shutters will fit easily on all cameras. Depends on weight, size of lens, etc. for example, one lens I have in a #5 shutter, I fint th elens itself a wee bit too heavy for my Tachihara extended all the way out. also, on my Super Speed Graphic, the lensboard there is very slightly recessed, just enought to jam up getting at the iris stop.
However, on my Crown Graphic, or my Graphic View monorail - not a single issue, works just fine. I guess that one reason why I have more than one - 4x5 camera.
Back to Ektar lenses, as a general rule, excellent. You will run into some issues, so look before you leap. These problems gnerally are:
1) excessive cleaning - I've seen many wonderful Ektar lenses near ruined by people who used them so much and litterally scrubbed the lens surface to ruin;
2) Shutters. Usually the Supermatic, Ilex and Wollensak shutters provided with these lenses were pretty good, but agian, years of use and abuse - just simply too many miles.
3) Image circle to small. The 127mm Ektar is a prime example. Coverage on Ektar lenses is pretty good, fantasic on the WF Ektars, but with the 127, it was made originally for 3x4 or 120 format size, but hte image circle was soo good it barely covered 4x5, so it used used on mnay press cameras for 4x5. I've seen the same sort of thing on larger formats, the lens designated to cover 8x10 might barely do so, becuase maybe it was originally designed to cover 5x7 with movements.
4) overpriced sometimes. I've seen 135mm WF Ektars sell for more on Ebay than a good used 135mm Rodenstock Sironar - N or S. That's exactly why I sold my 135mm WF Ektar and bought a new 135mm Sironar.
good luck
joe