Nvidia-304 driver not installing correctly on Lubuntu 16.04

For the past day I have trying to get the Nvidia drivers to work on my 10 year old PC running Lubuntu 16.04.6 LTS as recommended here. The automatically installed drivers did not work, so I typed glxinfo and all I got was

Xlib:  extension "GLX" missing on display ":0.0". Xlib:  extension "GLX" missing on display ":0.0". Xlib:  extension "GLX" missing on display ":0.0". Xlib:  extension "GLX" missing on display ":0.0". Xlib:  extension "GLX" missing on display ":0.0". Xlib:  extension "GLX" missing on display ":0.0". Xlib:  extension "GLX" missing on display ":0.0". Error: couldn't find RGB GLX visual or fbconfig Xlib:  extension "GLX" missing on display ":0.0". Xlib:  extension "GLX" missing on display ":0.0".  Xlib:  extension "GLX" missing on display ":0.0". Xlib:  extension "GLX" missing on display ":0.0". Xlib:  extension "GLX" missing on display ":0.0". Xlib:  extension "GLX" missing on display ":0.0". Xlib:  extension "GLX" missing on display ":0.0". 

I have trawled the internet, following guides such as this one and many more very similar ones, mostly advising me to install nvidia-304 as opposed to nvidia-304-updates, the only two differences I can see between the two is that the nvidia-304-updates package runs at 800×600 resolution whereas the nvidia-304 package runs at (I think) 1280×800. My monitor’s resolution is 1280×1024. More importantly, when running the last command in that sequence sudo nvidia-xconfig I get left with this:

Using X configuration file: "/etc/X11/xorg.conf". Backed up file '/etc/X11/xorg.conf' as '/etc/X11/xorg.conf.backup' New X configuration file written to '/etc/X11/xorg.conf' 

But that’s besides the point. why are the graphics drivers not installing correctly, and how do I install them correctly?

FYI here are my system specs copy-pasted off my linked question, ignore OS, Kernel etc:

System information report, generated by Sysinfo: 27/05/2019 17:18:20 http://sourceforge.net/projects/gsysinfo  SYSTEM INFORMATION     Running LinuxMint Linux, the LinuxMint 19.1 (tessa) release.     GNOME: 3.28.2 (Ubuntu)     Kernel version: 4.15.0-20-generic (#21-Ubuntu SMP Tue Apr 24 06:16:15 UTC 2018)     GCC: 7 (x86_64-linux-gnu)     Xorg: 1.19.6 (25 October 2018  04:11:27PM) (25 October 2018  04:11:27PM)     Hostname: jeremy-ixtreme-M3720     Uptime: 0 days 0 h 49 min  CPU INFORMATION     GenuineIntel, Intel(R) Core(TM)2 Quad CPU    Q8300  @ 2.50GHz     Number of CPUs: 4     CPU clock currently at 2000.092 MHz with 2048 KB cache     Numbering: family(6) model(23) stepping(10)     Bogomips: 4999.94     Flags: fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush dts acpi mmx fxsr sse sse2 ss ht tm pbe syscall nx lm constant_tsc arch_perfmon pebs bts rep_good nopl cpuid aperfmperf pni dtes64 monitor ds_cpl vmx est tm2 ssse3 cx16 xtpr pdcm sse4_1 xsave lahf_lm pti tpr_shadow vnmi flexpriority dtherm  MEMORY INFORMATION     Total memory: 7724 MB     Total swap: 2047 MB  STORAGE INFORMATION     SCSI device -  scsi3         Vendor:  ATAPI             Model:  DVD A  DH16AASH       SCSI device -  scsi4         Vendor:  ATA               Model:  ADATA SU650           SCSI device -  scsi6         Vendor:  Generic           Model:  USB SD Reader         SCSI device -  scsi6         Vendor:  Generic           Model:  USB CF Reader      HARDWARE INFORMATION MOTHERBOARD     Host bridge         NVIDIA Corporation MCP73 Host Bridge (rev a2)         Subsystem: Acer Incorporated [ALI] MCP73 Host Bridge     PCI bridge(s)         NVIDIA Corporation MCP73 PCI Express bridge (rev a1) (prog-if 01 [Subtractive decode])         NVIDIA Corporation MCP73 PCI Express bridge (rev a1) (prog-if 00 [Normal decode])         NVIDIA Corporation MCP73 PCI Express bridge (rev a1) (prog-if 00 [Normal decode])         NVIDIA Corporation MCP73 PCI Express bridge (rev a1) (prog-if 00 [Normal decode])     ISA bridge         NVIDIA Corporation MCP73 LPC Bridge (rev a2)         Subsystem: Acer Incorporated [ALI] MCP73 LPC Bridge     IDE interface         NVIDIA Corporation MCP73 IDE Controller (rev a1) (prog-if 8a [Master SecP PriP])         Subsystem: Acer Incorporated [ALI] MCP73 IDE Controller  GRAPHIC CARD     VGA controller         NVIDIA Corporation C73 [GeForce 7100 / nForce 630i] (rev a2) (prog-if 00 [VGA controller])         Subsystem: Acer Incorporated [ALI] C73 [GeForce 7100 / nForce 630i]  SOUND CARD     Multimedia controller         NVIDIA Corporation MCP73 High Definition Audio (rev a1)         Subsystem: Acer Incorporated [ALI] MCP73 High Definition Audio  NETWORK     Ethernet controller         Realtek Semiconductor Co., Ltd. RTL8101/2/6E PCI Express Fast/Gigabit Ethernet controller (rev 01)         Subsystem: Acer Incorporated [ALI] RTL810xE PCI Express Fast Ethernet controller