You must be one lucky guy. The pin came out and did absolutely no damage. If it made it to the oil pan, it won't bother anything, but it sounds like you already removed it.
I wouldn't bother replacing the pin. It's only used during engine assembly to locate the gear case to the engine block.
If you still have the gear case cover off, you may want to torque the remaining gear case to engine block bolts. A lot of guys remove one at a time, clean the threads with brake cleaner and a shot of shop air and apply a bit of loctite to the threads. A few bolts are hidden behind one of the gear blanks (can't remember which one) and you may have to bar the engine over to gain access to them.
It may be a good time to buy that lottery ticket.
Good luck with repairs.