1. Does this oil pump drive gear have the good wear pattern? Is it worth trying to remove it to use on a new pump?

2. What's with the one grooved bolt on the flex plate?

3. Looks like my water pump was missing a bolt for the last 5 years at least.

you don't remove the gear and swap it among pumps. if you replace the pump, it will come with a new gear.
the grooved bolt on the flex plate just tells me it's a "grade 8," SAE threaded fastener. (as opposed to metric) Mopar used both styles of bolts over the years, being that you have both on one particular engine means just that someone has been there before and probably had a mix of bolts-- or maybe they lost 1 and this was what they had on hand to replace it.... I wouldn't worry about that..... as long as it unthreads OK, and isn't a coarse thread bolt jammed into a fine thread hole or something, which I doubt...… like I said Ive seen both head styles on various Chrysler products over the years, I think the one with the grooves is an "older style".

Yep. seen lots of these on 60's mopars...like Don said the previous owner must've lost one and
they used a spare that was lying around.
Yeah and No.... since the new Melling pumps come with a softer gear, if the engine is going to do some long duration or
high rpm driving, its recommended to swap the OEM gear to the new assembly as it will last longer (Doc used to have as number
of gears he offered that were hardened for race use). That being said... I have not had a problem with the soft gear on a new
melling pump on a strict daily driver...if he can get an OEM oil pump, he won't need to swap the gear either (not easily found or cheap anymore).

Another thing to consider when swapping gears is that over the decades most oil pumps have an interference fit of the gear on the shaft, but
there are a few OEM and Aftermarket that have the gear and shaft slotted for a key...which will limit things since you can't swap the keyed and
non-keyed gears dues to the key slot and the shaft diameter.

The pattern on the gear is down the middle and I don't see much cupping, but we aren't looking at the teeth to see wear on the cross section
of the tooth.

FYI.

More stuff I found today:

1. The timing gear cover had a nice smear of mayo on it. I didn't wipe it on there. There was also some on the front and rear ends of the valve cover and the inside of the oil filler cap.
2. The timing chain has about 1/2 inch of slack. Also, there was no oil slinger. Anybody got an extra?
3. The rocker arm contact points don't look overly worn to me. The machinist was pretty sure they would need resurfacing or replacing. Thoughts?
4. One or two of the pushrods have a bit of pitting along the middle of the shaft. I suppose I'll be replacing them anyway.
5. Here's a shot of the camshaft. I didn't expect so much blackened buildup on the lobes.
6. Here are some pics of the valves. Anybody see recession?

Valves don't look recessed to me, but a couple of those might be burnt. Hard to tell from a picture if it's just built up crud, though.

The rocker tips look fine to me, but holy crap do you need to clean those rockers. I would string them all together on a wire coat hanger to keep them in order, and bring them to the machine shop to be hot tanked. After you get them back, you can probe the oiling holes with a piece of wire, sewing needle, etc. Also a good idea to clean the shaft.

Timing chain is worn out; you'll want a new one. Best to replace both gears at the same time. However, for a street engine I've certainly been lazy and re-used the old crank gear because I didn't want to press a new one on. Definitely a good idea to replace the original plastic-tooth cam gear. Someone around here probably has an oil slinger they don't need; I'd make a separate post in the "Parts Wanted" section.

Not sure what to make of the mayo. Any indication the water pump was leaking due to the missing bolt? Any more mayo in the oil pan? What did the head gasket look like?

_________________
Somehow I ended up owning three 1964 slant six A-bodies. I race one of them.
Escape Velocity Racing