For some reason the drive gear on my distributor sheared its roll pin. I'm replacing with new distributor. But all the timing is off now so I will need to turn the engine to realign everything (looking to get #1 to TDC). What size is the nut on the front of pulley attached to the crankshaft?

 

15/16 is the crank bolt size
Same thing happened me
Mine was a cheap China part with a brittle solid pin

 

When I pulled the dizzy the drive gear stayed behind and I had to fish it out with a pair of long-nose pliers. When you consider that the oil pump is driven by the dizzy and losing the oil pump is akin to a massive heart attack for the engine, that little roll pin holding the gear to the shaft seems like weak design. On the other hand I guess if something has to break, that's probably the least difficult to repair. I want to replace the oil pump, but from what I've read it's a real PITA.

 

It sure is a PITA to get the pan and the oil pump out
I have had the pleasure several times
I am still waiting for the 3 little pieces of the broken pin in mine to destroy the engine

 

I decided to swap in a double roller straight up timing chain on my 86 460 and when I pulled the front cover and saw a chunk of iron missing I thought WTF? The engine only had 30k original miles on it and I'd driving it over 4k miles at that point without issue and never saw glitter in the oil that I changed at least once per year or 3k miles. Cover had never been removed prior to me though. Looks like Ford just whacked it with a hammer to clearance for the drive gear.

 

At least that is a roll pin and not a solid piece of rod
That is a Ford one?
Quality is job none like they always told us

 

Factory installed. It had an 8/86 build date.

 

That chipped looking area is just from how the block is cast. The roll pin usually breaks because something got in the oil pump or the gear is not installed correctly. The gear should sit and ride but not be forced against the block. The gear should never be hanging up in space. Yours should be installed correctly from the factory so I think that I'd be leery of it doing it again. Most of the time it breaks the pin and the engine quits running which doesn't hurt a thing. When the pin is extra strong and something jams the pump it twists off the drive shaft, the pin stays intact and the engine keeps on running without oil pressure.

 

Clean off the harmonic balancer and put a nice white mark on the TDC mark and another at 10 degrees advanced and another at 13 degrees advanced. These are good starting points for timing a 460. Pull number one plug, stick your finger in the hole and bump the starter over using a wire jumper at the starter solenoid. Once you feel compression, bump the starter until the TDC timing mark lines up with the timing pointer on the timing chain cover. It might take a few tries till you get it. When you have the TDC lined up with the timing pointer install the distributor with the rotor pointing at number one plug wire on the distributor cap. Couple of Tips. Pull all the plugs, makes turning the engine over with a socket much easier. And give you a chance to inspect the plugs. When you pull the distributor raise it about an inch and rock it back and forth to make sure the oil pump drive shaft has stayed in the oil pump and does not fall down into the oil pan. If when you pull your e-bay HEI and he drive gear stays in the engine, don't panic just retrieve it with a needle nose pliers. Before you bolt down the distributor check for a little end play in the shaft by pulling up on the centrifugal advance just a bit of up and own clearance is needed between the gear and the block at the bottom. If the gear is jammed tight against the block it will wear out prematurely. Maybe 10 thousands is plenty of up and down movement. Sheared pins can be caused by a heavy duty oil pump and heavy oil, crap in the oil pump and some times **** just happens.