Hey Chris,
Welcome mate...
Ive got 2 model 6 going currently 1 original 1 modified.
Ive only seen 3 catchers come up in the last 2 years,and ive never seen an nos set of wheels for Sheerline,in fact Sheerline would have to be one of the hardest mowers to get NOS parts for. Just keep trolling Ebay and poking around.
Im only in need of front axle clips for my original,and I also need decent wheels,but like you said the fun is in the hunt and more often than not in time...we get rewarded for our efforts. Good luck and cant wait to see your progress images.