Just remember: if you up the APAP amount, keep a watch out for your liver. If you take these meds chronically (daily) then try not to take more than 3g's, 4g's max of APAP per day (that would be 6-8 of the 10/500's or 5-6 of the 10/650's )
If this still doesn't seem to work for you or you need more than 6 or so hydro's per day for your condition, then maybe look at the new ibuprofen compund, Vicoprofen (200mg Ibuprofen, 7.5mg Hydro) - I would suggest compounds but it seems the lower dose APAP doesn't work for you as well (since you said you had good results from 7.5/750) Why don't you just go back to the 7.5's if they worked for you the best? 10/325 is not the best for everyone, just safest for the liver if you take the pills regularly and chronically.

sidenote: All the meds I have received from DatamarkHRI (10/500 usually) have been of the freshest quality of any pharmacy I have ever received from (considering they come straight from the sealed containers)