Assuming you already have an elf system:
Carefully remove all traces of gcc including the symlinks.
(watch out for cpp script and 2.6.3 or whatever symlink)
Carefully remove all traces of library stuff under /usr.
Get the precompiled gcc 2.7.2, and untar it from /.
Get the precompiled make and install right over the old one.
Get the precompiled libc and untar it from /.
Make a symlink: "ln -s /lib/YourNewLibc /tmp/LibcLink"
Move it onto the old one: "mv /tmp/LibcLink /lib/LibcLink"
Remove whatever the old link pointed to.
(you can only do this if the major number was the same)
Run ldconfig if it's not in your boot scripts.
Reboot.
Get a new sendmail and uugetty (precompiled?).
Assuming you have an a.out system and want to have elf:
Boot install disk of favorite distribution.
Mount your harddisk.
Change to the root of the harddisk ("cd /mnt" maybe)
Make a directory called old.
Put everything there: "mv * old"
Start the install program, but do not let it format your disk.
(tell it where you mounted the disk, or unmount first)
Install.
Reboot and salvage all the files you want from /old.