Looks like you have satge III heads. Here's you some readin. You'll notice that if they have MOPAR cast into them and an M after the casting number, they are not original Max Wedge heads.
http://racehemi.maxwedge.com/topics/heads.php
For your reading pleasure:
"1964 Stage-III Cylinder Head - part # 2406736 / casting # 2406518
The Max Wedge cylinder head 518 castings for 1964 had only a few changes incorporated into them over the 1963 - 286 castings. The more notable changes were the addition of two more valve cover bolt areas for improved gasket sealing. The other notable was cast in towers for rocker shaft positioning. These changes were incorporated across the board into big block cylinder head castings including standard engines from 1964 to the end of big block cylinder head production. Along with these casting changes the Stage-III cylinder head included the machining improvements that were added to the Stage-II heads in the late 1963 production period.
Below is a newer Mopar Performance head but for visual purposes it is very close to the original casting from this vantage point. Notice the cast in rocker stands and six bolt valve cover configuration. It is important you know the difference between original max wedge heads and the newer replacement heads like below. Only replacement heads have "MOPAR" cast onto them like the head below or have an "M" at the end of the casting number. Also, no original heads have pentastars cast onto them either. Not all recent replacement heads have all three of these "tell's" but they always have one or two of them. Look out for these identifiers when buying heads represented as original 62 - 64 castings. There are guys throwing these replacement heads on sites like ebay claiming they are original vintage or NOS original period heads to scalp unsuspecting buyers. I had a very good friend get taken like this to the tune of 2500.00 for a pair of heads you can buy today for half that or less. I warned the guy three days before his auction ended about this fact and he made no attempt to pull the auction or add information to his listing."
"Like I said before, the first picture of three directly above is very close to an original 64 vintage Stage-III head so you can see the cast in stands and six bolt valve cover configuration. If you then look at the bottom two pictures you will see casting marks only on replacement heads made roughly in the last four years or so. Notice in the bottom two pictures the lack of cast in stands. These replacements came in a couple of different configurations so be on the look out when buying what is represented as original from back in 62 - 64. These new heads will work just fine although they don't flow as good as the originals out of the box without some porting work. If I get a chance to get some good pictures of an original Stage-III I will add them later.
Conventional wisdom today is that the 1.88 exhaust valve was to big and restricted the intake valve size from going bigger for improved flow. Today the hot set up for racers is the original max wedge port size with a 2.14 or 2.18 intake valve and 1.81 exhaust valves. This also a more favorable valve combination if you are building a large cubic inch stroker.
It is important to mention that all three years of Max Wedge cylinder heads used cast iron adjustable rocker arms. There are also specific changes reagarding combustion chamber volume that I won't be getting into at this time. Everything else is pretty much the same. Now you know what I know about Max Wedge cylinder heads.
Note: * - the remarks above accompanied by the preceding * regarding the Stage-II cylinder head improvements were taken from an internal Chrysler "Production Information Bulletin" dated June 13th, 1963 (pages 4 and 5)."
