The larger holes are threaded and the smaller holes is just drilled (no thread). Located on both left and right chassis rail.
Any ideas?

Their not for crossmember or for swaybar as they are already installed by the look of the pics. What year model Capri is it as my 71 models don't have those holes.

Some Capri came with a card board shroud - a splash shield - v few left for good reason

Can't imagine such large threaded holes were made to anchor a flimsy splash shield......
could be "rails" from a different car like Escort or Cortina (after accident) or option to change "wheel base"(long bow)?

From memory - 4 5/16 unc bolts used

1. Small unthreaded holes might be datum points for jig assembly.
2. From memory - 4 5/16 unc bolts used - I've used mine for a splash/airflow shield I made up, fitting from the bottom lip of grille crossmember (Z clips) to four bolts to chassis rails.  See part number 69EB 6775 AB Shield Engine Splash.
Sorry can't find a pic - trial and error with a piece of cardboard. I saw a factory original at a show years ago.  Possible creates a low pressure area to help draw air thru radiator, or at least stop splashes up onto the engine. See modern cars for examples !!!
Do I get 2 points ?

Not sure who gets the points, but it is a 1970 V6. The threaded holes are similar too the cross member bolts maybe a bit  smaller than the front end bolts (will check the size tomorrow ). All the front end is fitted, cross member and the sway bar, car chassis rails appears to be the originals  Looks like a locking tag hole next to the threaded one. Never seen any splash plate on a 1970 or at any car at all? anybody got any pictures? How do I track down part number accapmad???

Here tis

I think this is the Capri one - u can see the 4 bolt holes top of shield - 2 on each side...