[D-CEL]

Yes the 385 series BB (429-460) will fit in an FFR and is a fantastic engine platform. Many great cylinder heads, inexpensive long stroke cranks and very strong factory blocks make it the best “HP per Dollar” big block.
First decide how much power you want and where you want to make it.
Here is a good solid street BB
2 bolt block bored to 4.390 with a 4.500 stroke cast crank would make 545 C.I.
At 10.5-1with a hydraulic roller cam and a set of P51 heads.

Should be plenty to scare the crap out of you and turn your tires into piles of smoldering, giggle inducing, black powder goodness!!~
a BIG drag radial might help.....

Jason