Wesley,
I shoot the MFX 400's and use 100 gr. brass inserts, 75, 100 & 125 grain steel BH adaptors with 190 and 200 grain Grizzly's, so 300 to 400 grains up front easily, depending on which combination I use, etc. Look to 3 Rivers and Kustom King, there are heavier field points offered from both companies. You shouldn't have any problem reaching your 700 grain benchmark. There are endless possibilities for what you want to accomplish. I might add that I hot glue my inserts into the shafts, so I have the flexibility to change them up for tuning purposes.
Good luck!
Kris