I built one in 243w years ago using a DSArms 20" barrel. It shot better than any of the 308 G1 FAL's I put together back then. If memory serves me, I was using 70gr. Nosler Ballistic Tips and was able to keep 5 rounds inside and inch at 100 yards pretty consistently and cycled perfectly. No longer have the rifle or any of the FAL's I built or purchased, moved on to the AR10 platform where accuracy is much more consistent across the board.
Give it a try you may like it.