OK, Isky cam basics for any 691 V-twin:
Stock or near stock Engine- #3 grind. Good for 5000rpm
Billet rods and flywheel, 1/4" valve stems- #4 grind. Good for 6200rpm, but you will be breaking an occasional rocker or push rod.
Full out w/ roller rocker arms- #1 or #5 grinds. Both will go 7500rpm+. The 1 has more bottom, the 5 more top.
To fully utilize the big grinds, you need to have carbs done right and excellent heads. Also, exhaust must be right.
Bert