More lift is (in general) good, remember that you may need to blend in some metal at the radius of the valve pocket, and/or plunge cut the relief deeper. The compression loss will be very minor.
More overlap is another story. All the original SV cams (except WR etc.) have very little, so adding some is safe, but a change in lift with the same lobe centers and duration (as in Joy, quoting from Steve's archived post: intake 24-54 degrees, exhaust 54-24, overlap 48, lift .460".) will increase the effective overlap (i.e., area of both valves open).
Things to be avoided, in order of priority:
1. late intake closing (not as important with large motors, strokers, short rods, high compression)
2. late exhaust closing
3. early exhaust opening
Extending the duration significantly on the original lobe centers will cause all 3. For best effect, a big change in intake duration should also be advanced (early opening), but this requires either a new lobe or re-timing the cam.
If you're going to use more OL (and tuned exhaust is useless without it) on a Linkert you need to learn how to mod it. Anyone who advises "increase the main jet size" hasn't a clue.
Mikuni is easier but still needs some work. S&S, Kei'Hin, Bendix, SU, CV: good luck.