old ati question

[trinidad]

I have an old Dell optiplex 320 which I have intsalled LL on for friend. I had Deb 9 on it for a while and was able to deal with its quirks. It apparently only alows a pre-boot resolution of 640X480 which is fine for the grub menu though in Linux Lite it curiously displays a Deb 8 splash. I'll hide grub anyway before I give it to my friend. I have not worked with plymouth much in LL other than to change the boot splash on a few systems. On this ati card the boot splash does not display correctly even from live cd in LL or Ubuntu LTS. I could change this in Deb 9 by enabling the old black screen text with three boxes basic splash. Can I script for Lite boot to display at 640X480. I realize it's coded for best resolution seeking but this old card will not allow the splash to display at anything but a fixed 640X480 resolution. The lightdm splash displays fine at 1280X1024 as does the booted LL system so the card and the plymouth script serve their intended purpose. As this computer is intended for an inexperienced user I need to correct the splash problem in pre-boot. The plain black three box splash worked for Deb 9 but I know it's not the same as the one in LL. Also I have yet to figure out changing plymouth themes in LL. Will my Deb 9 scripts work?

Addition: As I suspected normal Debian commands and scripts don't work. The new question is: If I remove plymouth-themes altogether will the system still boot and display the lightdm splash and login after loading? I can't send a computer out of my shop with the globbed up mess this machine is making of the plymouth boot splash. I wouldn't be resorting to scripting if I hadn't tried every other alternative. I did resolve the mysterious Deb 8 grub menu splash to a nice gray now.

TC
sorry for the long question