To do long exposure astrophotography, you will want to upgrade in the following areas:
focuser - needs to handle the weight of a camera plus guider diagonal - check for good illumination across desired film size tube - can't sag mirror mount - mirror can't suddenly shift; also, mirror may need to be moved forward, affecting diagonal size counterweight system added improved finder adding some sort of guiding arrangement
Now, to the mount. Placing a 10-13" dob on an already inadequate 6" mount (sorry about the bluntness, but my opinion is that this mount is too shaky for long exposure photography and the drive will need real work to track smoothly enough - also, what are you going to do about the declination corrections?) is going to be pretty iffy. A guy in our club once fitted a light weight 10" to a 6" Meade equatorial, but used only visually.
My experience has been that to do astrophotography right, you pretty much end up rebuilding the whole scope, though, there are those who buy all by staying in the standard SCT product lines, with success.
Please feel free to post questions regarding scope rebuilds here on atm. I think this is a very pertinent subject: others will correct me if I am wrong. This is not a good thing for infrequent posters to be scared to post for fear of being flamed. We are here to help each other and share ideas. No one is an expert on everything. We all learn from each other. Yes, sometimes (oftentimes) we have strong opinions, but a lot of that comes from having walked down the path and made mistakes that we earnestly wish to help others learn from and avoid.
Mel Bartels