Nathan, according to the shop manual the F8 had 2 tranny options - a regular 5 spd and a 5 spd od. 1st, 2nd and Reverse were spur gears. 3rd, 4th and 5th were helical gears.
The gear ratios only gave 2 more granny gears. Third gear ratio of 2.40:1 was similar to first gear in the F1 3 spd. So you wouldn't gain anything if you could even bolt it up. I haven't seen one, but I wonder if the tranny for the 8EQ matches the 8RT bellhousing??
I think you might do better to look for a T5 or an OD from a mid 80's pickup.
My 51 ford truck has the shifter on the floor, so I think it is a 4 spd. But it is all so a double clutch which I would like to get rid of. On the flat-o website it says the adaptor may work with later engines. Did the y-block still have the same transmission housing?