Hi Steve,
Hope you don't mind, I put a subject in the subject box for your post...
As far as through-put issues with your dispenser, why not print your epoxy. You would do the whole board in well less than 30-seconds, and have much better accuracy and consistency than you could ever expect from a dispenser.
As far as high temperature pastes go, you would need one of the high-lead alloys in order to be above the typical solder pot temperature of 500° F (260° C). Getting these alloys in paste form is going to be challenge as well, you can bet that it's going to be a custom order with a minimum buy too.
A few of those alloys are:
° F ° C
Sn10Pb90 514 - 576 268 - 302
Sn10Pb88Ag02 514 - 570 268 - 299
Sn05Pb92.5 Ag2.5 536 280
My two-cents...
-Steve Gregory-