All gears or only certain ones? Weak syncro(s)?
My 5spd swapped Aristo is a bit difficult when shifting from 3-2, but otherwise is pretty good. If I double clutch it's definitely easier. The syncro is known to be weak on the R154 transmissions, so I'm not surprised I'm having a bit of trouble. Obviously, this doesn't exactly pertain to your vehicle, but thought I'd post it if you are having a similar issue