running old binaries on -current

every now and then, for fun I run up a chroot of freebsd 1.1. or 1.0 
under a chroot.  Usually hillarity ensues with teh 15 second kernel 
compile and the 4 minute make world.

in -current I can't do that any more.. any binary just exits with 'Abort'.

I think I last tried it in 7.0 or there abouts.

I have options COMPAT_AOUT and COMPAT_FREEBSD4 through COMPAT_FREEBSD7

does anyone else have any ideas as to what may be needed?

I vaguely remember another option but I am not seeing it at the moment.

For those of you who do not remember, 1.0 had a.out static binaries only.