Actually I feel confident in your gpd skills now hehe. I will be on chat if you wanna talk but, Its really simple.
You should have placed the 1.8 backup where your other one was. ( externel_sd/clockworkmod/backup )
Reboot into recovery using rom manager or flashify ( from off position you can also boot into recovery by holding vol+ and power)
go to: - backup and restore
go to: - advanced
restore from external_sd
go to: the 1.8 backup file
go to: - restore kernel
after you do that you should have a (+) next to: - restore kernel (+)
double check that only the kernel has the (+) and then:
select: - Start restore
and you should now have 1.8 kernel installed.
This will give you 1.8, but skelton ( creator of Legacy ) also included other "tweaks" to the rom that help. So my suggestion would be to install from scratch. A fresh install of legacy rom 1.8.
If you do want to go that route I could walk you through that as well. It would involve:
Flasing Legacy Rom.
REFlashing CWM Recovery ( it gets overwritten on the last step so we have to reinstall )
Install Kernel Aduitor
and maybe some other stuff.... but your rig will be prime $$
Either way let me know. You know where to find me
Re-install Rom Manager