[FWB]

Agree with Tom, it could be a date code that was written wrong.
68 was the first year for the 385 series but my knowledge stops at the lincolns.
in 68 the 460 in the lincoln (optional) did have a crank mounted ps pump.
so i suppose the t-bird would have been similar.
pics and a better read on the casting date

a little birdie in my head is telling me there weren't any 429's in 68, only the 460, could this be a 428 your looking at