I doubt that your firing pin length has much to do with the safety lever engaging or not. I am pretty sure that you could saw off the front 1" of the Mauser firing pin, and the safety lever would still function properly. The firing pin goes into the cocking piece. When the action is "cocked" - the cocking piece is held back by the trigger sear. If the faces of the cocking piece or the trigger sear are worn enough, the cocking piece is too far forward - meaning the safety lever can not grab on to the upper shoulder in the cocking piece - so, could also be the safety lever bevel, or the cocking piece shoulder. An old school armourer would have enough spare parts to just keep swapping out parts until he got a combination that worked - a "gunsmith" would re-build / re-hone the offending part so that it worked properly. I have that going on with a commercial Mauser 98 here - I am attempting to install a military two stage trigger and get the safety to work - is on about the 5th sear so far - all are too long - trying to get one that fits - Plan "B" is to start honing on one, to make it the correct length for the safety to grab on the cocking piece. The Mauser safety needs to lift the cocking piece face away from the trigger sear as it engages - you want the trigger, OR the safety, to hold the cocking piece back - not both at the same time - not safety AND trigger sear both engaged at the same time.
