Welcome to the board.
If your DA has a square label, it was made between 58 and 69, 70-72 had round labels. If it's shinny chrome, 64-69 and if it has a yoke screw that looks like a tire 66-69. It really does not matter what year it was made, internally they are all the same but it's always fun to narrow it down some.
This board is Vintage Double Hose and where you can purchase all parts you need. Besides the Phoenix and HPR, you will require a few more parts to get it operational and there are some that are nice to have. I will list the parts and give you some explanation why you need/want them, it suffices to say that ALL rubber parts have to be replaced, none of them stand up to 45 or more years of aging and are still good enough to dive with. With a Phoenix and HPR you are building a very good breathing regulator, don't scrimp on old rubber goods.
The parts you will require are, (they are NOT optional no matter of how good the originals look
:
DA service kit - it does not come with a HP seat but you will not need it if you are installing a Phoenix
DBE (duck bill eliminator) or a duckbill -these regs have an exhaust valve in the top can that must be replace, you can use either the DBE or
a standard duckbill considering you are upgrading to a Phoenix and HPR, I would highly recommend
adding the DBE...it's just a $10 difference, is easier to install and preforms better
Mouthpiece valves (aka wagon wheel valves) - these are mushroom shaped silicon valves in the mouthpiece, guaranteed the old ones are bad
Hoses and mouthpiece I realize yours might look OK but again, these rubber good do not stand up well over time, you are building
a very good regulator, why dive it with crappy hoses and mouthpiece...and frankly the old rubber ones taste bad.
Nice to have:
Band Clamp the C clips on these regs are a pain to remove and install, plus they tend to scratch up the chrome if you
are not very careful. The band clamp is easy to remove and install which encourages you to open and
properly inspect and clean the reg....none of my regs go without one unless I am trying to keep it original.
Hose clamps I am listing them under nice to have because most of the time they are OK but personally, I replace them too
many times they are brittle and will break so it's nice to have spares.
Beyond parts I would suggest you take the time to read and learn as much as you can about DH regs, both from a service and a diving perspective. They are fairly simple to service but it does take some understanding of how they operate to do the job correctly. Likewise, diving them is easy but is different and requires some different techniques to get the most out of your reg. For example, the regs MUST be properly located on your body. Most modern BCs do not allow this. The cans (metal body) have to be low and close to the body and REMAIN there through out the dive, modern BCs don't do this well (or at all). Breathing a DH is also different for most people, rather then a shallow, quick breath, a DH works best with long slow inhales and exhales. The regs will give you air with a modern BC and breathed improperly but you will not like the experience nearly as much.
There is a lot if information available on this site, both in the "Manuals and Catalogs" section as well as threads members have posted over the year, do a search and read all you can, the better informed you are the easier this will be. And ask questions, by far the best DH divers on the planet are on this board. We don't just talk about them we dive and restore them (and build new things) all the time.
And I may as well comment a little on tools, there are some must haves and some nice to haves. Besides the standard hand tools, on the must have list are an IP gauge and circlip pliers. On the the nice to have list are a number of tools that will make your life easier. You need some way to hold the reg body and remove the body ring. You can really mess up the body and interior of the cans if you are not careful using makeshift tools. The HP nozzle assembly (both the original and Phoenix) are a real pain to reassemble without the proper tools, it can be done but it's a huge pain. I make the tools for these regs. You can contact me for a catalog (or download it from the "catalog and manuals" section of the board)
Above all, ASK QUESTIONS. We have all been where you are and are willing to help if you will just ask. We enjoy photos of your progress and they help up direct you so keep the camera handy....