That was a very concise and well-communicated request. Wish all the questions I get were so well done.
Okay, no, OP does not carry focusers that would fit a reflector, but I have found them at Orion, in the past and some other smaller online companies that sell telescope
building components- try doing a google search for telescope
parts or telescope
building. If all else fails, you could probably find a cheap reflector (but it must be a reflector) at a garage sale and rob the focuser of of it. JUST BE SURE the focuser you get is a focuser that takes 1.25" eyepieces and you have the second problem licked. Converting to 1.25" from ".965 inch via an adapter poses problems. First, the adapters are difficult to find - only a few are made and those are often backorder. Meade
makes one in the AD-2, #07501, but that only works with focusers that have enough back travel (1.5"). May not work in your older DS. Personally, I would just try to replace the entire focuser and do my best to find a better quality focuser. You may have to drill new holes and so on, but a new focuser would be your best solution.
Finders are an easy fix. Just get a red dot
like the Celestron Star Pointer
or a good aftermarket red dot. These are much better choices than the cheap little 6x30 optical
you typically find on telescopes
in this class. You can actually use velcro or double-sided tape to attach the Celestron
or other red dots, so no drilling required.
Okay, I'm going to tell you straight that that scope, in particular, that mount, is less than ideal for astrophotography. You will be able to take short exposures of the moon and planets, but no long term exposures of deep-sky objects and those are the typical targets
of choice for most astrophotographers. The problem is field rotation. The DS mount will track the objects, but the computer in the DS needs to move the scope twice - up/down, right-left - as the object tracks across the sky in a gentle arc. This produces blurry images around the center of your pic. The middle of the pic will be relatively sharp, but the field around it will not. More expensive scopes
on fork mounts cure this with accessories called wedges or field de-rotaters, but not options you can add to a DS and, even if you could, these accessories cost more than the scope is worth.
More serious issue is the drive system, itself. That drive really doesn't have the kind of accuracy for really good long exposures. Good pics require a drive that allows you to make minor corrections in speed as needed. Lastly, there is a serious problem of weight. The drive is not designed for that kind of weight - you could damage the gears and motor and, yes, you will definitely need to jury rig the scope with counterweights.
The adapters are the easy part. A standard , prime-focus t-adapter and a t-ring for an EOS will get you started, but, again, you may discover that the focuser on your old DS does not have enough focus travel to handle these accessories.
Overall, I would I would suggest using your scope, as is, to learn the basics of telescopes
and astronomy. Upgrade the focuser and eyepieces, yes, but, even then, by the time you purchase more eyepieces and a focuser, you have already put more money in the scope than you can ever recover if you sell it. Your call, there. The finder scope is a must
Honestly, I would move on to another scope, though, before I tackled astrophotography. Not to say you cannot use a DS for astrophotography, but it is going to give you a lot of headaches and that is not something you want if you are starting out in astrophotography.