Jerry,the original distributer is held down by a pinch clamp,a flimsy thing.When the engine is running,the cam gear pulls the distributor shaft downward,but it is somewhat free to rise up on it's own,never an excessive downward force.
The Mini still has the locating collar like a small block or later 6 distributer? If so,when you clamp it down,the shaft and gear may be forced down by the bolt.This will grind up the oil pump,not good.Just make sure when installed,the it slips in easy,goes all the way down and the shaft(not the auto advance device)has a touch of play upward.
The machining tolerances can stack up wrong, be sure to check it out.
