I use a Cannon 8um inline ff just before the VP44. It is built for big race engines, AN-12 fittings and is diesel compatiable. They have a reducer AN-12 to AN-6. Presently I do not run the OEM ff.
I have a RACOR 690T right after the fuel line comes out of the tank before anything, lp, lines, anything.
In fuel filtering you want the water block filter to catch any free water (one fo the functions of the OEM ff element), and you also want the particle filtering.
My Racor does the free water block and 10um filtering, the Cannon does final 8um particle filtering of anything that might have sluffed off in the lp, lines etc.
Bob Weis