I have an A 200 mm f/4 but it was always disappointingly flat and unsharp on my 645N. I once tried it with the 1.4X converter (which is excellent in itself) and the results were terrible on film. I put it aside and never used it on the 645Z. Instead I got an FA 200 mm f/4 ... Wow! That is a superior lens, very sharp and contrasty for landscapes. I never tried the 1.4X converter on it as I use a 6X7 M* 300 mm f/4 (with a Pentax adapter) and a 645 FA 400 mm f/5.6 (both of which have a tripod foot that facilitates handling) for longer telephoto shots.
Picture of Ile-aux-Coudres in Charlevoix taken with the FA 200 mm f/4 and the 645Z on a tripod.