Motorcraft 4 barrels
Being mid 70;s carbs, they are likely 4300 series carbs.
The 4100 looks like two motorcraft 2V carbs welded together back to back. The 4300 looks similar to a quadrajet, but may or may not be a spreadbore.
4100 carbs are awesome, simple carbs that work very well on streetwise small blocks.
4300 series carbs are quite literally JUNK. The only value they have is for restoration purposes.
Those that say it cant be done should say so quietly, so as not to disturb those who are doing it.