When I had to replace my 501 cam a few years ago Tighe were charging almost the same as OEM for an exchange, so I went OEM. I now have a blank and I'll go with a Lineaweaver exchange if I ever need to do it again. I do hear that they do good work though.
When I needed to get my valve seats replaced after they broke up way back in 99 Sutto organised it with someone who does it around the Penrith area. The valves have basically never got out of adjustment since, except for the roller followers going and taking the cam. 23,000 km and untouched since with Delo 400 @+/- 5 hours. 33,000 km all up
Steve