Many people have been in this same dilemma. You can convert a 14BFF to 6-lug, but it requires custom machining on the hubs, axleshafts, etc. Converting to 8-lug all around is cheaper than this. You can not make a wheel adapter work for this. So here are your best options:
1) Embrace your 8-lug future. The nicer your wheels are, the more money you can get when you sell them. Buy a similar wheel in 8-lug, get some front 8-lug outers and you're done. Having that full float rear implies you might run some big meats, so jump to 8-lug right away before spending money on 6-lug stuff. About 6,000,000 guys on here will tell you to do this.
2) Forget about the 14 FF. Get a 14B S/F. The 80's ones will bolt in and can be converted to 6-lug with junkyard parts. Some 90's ones came in 6-lug and just need spring perches and shock mounts moved. Much easier than reworking the FF. That 9.5" rear is good for like 38"-39" tires.
In either case, search. The details of both have been posted here numerous times.