Max factory shortblock HP and RPM

[Gyro]

What is everyones thoughts on the maximum HP or RWHP potential and maximum RPM potential of a NA factory shortblock in a 3.8L V6 and then in a 4.2L V6 with the both of them being in very good condition?

[VCS_SSSTANG]

350rwhp
I wouldn't go over 6grand.

Max potential is like 280rwhp (H/C/I/builtmotor/longtubes/the works)